September is the month dynasty managers either love or dread. Rosters expand, the prospects you have been stashing since draft day finally get the call, and suddenly 40 plate appearances are doing the talking for a player you have been projecting for three years. It is the smallest sample of the season with a notable reaction, and every late-season debut sets off the same scramble in league chats: buy before the price jumps, or sell before everyone figures out it was a hot week.
The 2026 class gave us plenty to argue about. St. Louis Cardinals standout Joshua Báez homered in each of his first three big-league plate appearances, the first player in history to do it. Cleveland Guardians utilityman Angel Genao collected four hits in his first game, a franchise first. Seattle Mariners slugger-to-be Lazaro Montes hit a 474-foot homer in his second week. And San Diego Padres prospect Ethan Salas became the youngest catcher ever to appear in a postseason game, at an age when most of us were still figuring out how to do our own taxes.
But debut fireworks and dynasty value are not the same thing. So for the 12 notable hitters who made their MLB debuts after August 1, let’s sort through what the box scores said, what the underlying data said, and where each one sits heading into the offseason. All 12 should keep their rookie eligibility for 2027, which matters for leagues with rookie or prospect slots. For a starting point, I defer once again to teammate Martin Sekulski’s latest top 400 dynasty rankings, and the players below are listed in his order.
None of these samples clear 140 plate appearances, so read every number below with that in mind. Still, a few patterns stand out to me. The two catchers, Salas and Bernal, are ranked more than 200 spots apart, and their underlying numbers point in nearly opposite directions. The three best barrel rates in the group all belong to players ranked 369th or lower. And the player at the top of the list walked more than twice as often as he struck out. Let’s take a closer look at each.
OF Josue De Paula, 21, Los Angeles Dodgers
Debut: Sept. 11 | 31 AB | .323/.500/.581 | .258 ISO | 11.9% K% | 26.2% BB% | 199 wRC+ | .437 xwOBA | 1 HR | 7 RBI | 1 SB
De Paula was the headliner of this class before he ever played a game. MLB Pipeline’s sixth overall prospect spent all of 2026 at Double-A Tulsa, where he hit .303/.401/.547 with 27 homers and 31 steals. Then superstar Shohei Ohtani landed on the injured list, and the Dodgers did something they had not done with a position player in more than a decade: they skipped Triple-A entirely.
What followed was 42 plate appearances that looked more like a veteran’s than a 21-year-old getting his feet wet in the postseason push. He walked 11 times against five strikeouts, posted a .500 OBP, and his .437 xwOBA says the production was not smoke. His first homer came on Sept. 13 off Eury Pérez, 416 feet at 108.2 mph. His 19.0% whiff rate was the second lowest in this group, and he rarely gave away an at-bat. The power did not fully show up, with an 89.2 mph average exit velocity and a 9.7-degree average launch angle, but this approach gives me confidence that the power will come to light in 2027 and beyond. Dodgers manager Dave Roberts trusted him enough to carry him on the NLDS roster over Dalton Rushing, calling him a special hitter. While he only had three plate appearances in the postseason, he drew two walks in that body of work and was a huge net positive despite the NLCS sweep overshadowing him.
The only real question is where he plays. The Dodgers outfield still has Kyle Tucker, Teoscar Hernández, and Andy Pages, Ohtani is parked at DH, and Los Angeles has never been shy about adding more. That is the risk that keeps him at 43 in Martin’s rankings rather than higher. In 5×5, he projects as a true five-category bat. In OBP leagues, a 26.2% walk rate in a small sample aligns with a minor-league profile built on swing decisions, which makes him even more valuable. Buy at any price outside the top 40, and buy harder if a fellow manager is waffling over the depth chart situation.
CF Walker Jenkins, 21, Minnesota Twins
Debut: Aug. 28 | 84 AB | .226/.293/.393 | .167 ISO | 20.4% K% | 7.5% BB% | 92 wRC+ | .310 xwOBA | 4 HR | 10 RBI | 1 SB
Jenkins has been one of the safest-feeling bats in dynasty prospect circles for three years, the No. 5 overall pick in 2023 with five above-average tools and a hit tool to anchor them. The only thing that ever slowed him down was his body. He missed time in May and June with a shoulder sprain, came back to post a .940 OPS with 12 homers in 69 Triple-A games, and got the call when outfielder Byron Buxton’s hip flared up in the middle of the AL Central race.
The first 16 games were rough. He hit .089 and looked every bit like a 21-year-old seeing big-league breaking balls for the first time. Then he flipped it, hitting .385 with three homers over his final 10 games and moving into the leadoff spot. The final season line lands at a 92 wRC+, and the batted-ball data, like De Paula, is the soft spot, with an 85.0 mph average exit velocity and a 27.3% hard-hit rate, the lowest marks among the 12 hitters here. The approach held up, though. His 20.4% strikeout rate and 23.9% whiff rate are in line with the contact skills that made him a top-15 prospect, and his .310 xwOBA sits a touch above his .303 wOBA.
Jenkins had surgery around Oct. 1 to remove a bone chip and spur from his right elbow, and the Twins say he will be full go for 2027. It is a minor procedure, but it is one more entry in a medical file dynasty managers already watch closely. His 2027 job is likely but not guaranteed, with Buxton, Luke Keaschall, Alan Roden and Emmanuel Rodriguez all in the outfield mix. I love his long-term value, as that depth chart looks softer on paper than Los Angeles’s. If someone in your league is selling the .226 average and the elbow, this offseason might be your final window to buy without a premium.
C Ethan Salas, 20, San Diego Padres
Debut: Sept. 2 | 39 AB | .256/.275/.462 | .205 ISO | 22.5% K% | 2.5% BB% | 102 wRC+ | .227 xwOBA | 2 HR | 5 RBI | 0 SB
Salas signed with the Padres at 16 and has been the youngest player on nearly every field since. He kept the streak alive in September. Debuting at 20 years and 93 days old, he became the youngest catcher to reach the majors since Hall of Famer Iván Rodríguez broke onto the Texas Rangers roster in 1991. His 2026 minor-league season was the best of his career, a .296/.374/.448 line with 10 homers, 17 steals and a 14.3% strikeout rate across Double-A and Triple-A.
The MLB stint was a tale of two halves. He opened 0-for-15, then went 10-for-24 to finish the regular season, including a two-homer game on Sept. 16 that made him the youngest catcher ever to go deep twice in a game. On Sept. 30, he started Game 2 of the Wild Card Series against the Cubs and became the youngest catcher ever to appear in a postseason game. Now the caution flag. His .227 xwOBA was the lowest in this group by nearly 40 points, well below his .316 wOBA, and he barreled just 3.3% of his batted balls. The surface line was better than the contact, and he hit .125 in 10 postseason plate appearances.
The other surprise came on Oct. 17, when San Diego general manager A.J. Preller said of the 2027 catching picture, “I don’t think anybody’s going to be guaranteed anything.” Luis Campusano and Freddy Fermin are still on the roster, though Salas is the lone left-handed bat of the three. For dynasty purposes, none of this changes the long view. Martin projects him as a top-10 player at the position for at least the next decade, and his contact skills plus rare speed for a catcher make him a strong roto piece. In two-catcher leagues, he’s a cornerstone. Hold, and don’t let one month of xwOBA scare you off the 20-year-old catcher.
OF Joshua Báez, 23, St. Louis Cardinals
Debut: Aug. 15 | 100 AB | .230/.278/.510 | .280 ISO | 30.6% K% | 3.7% BB% | 113 wRC+ | .303 xwOBA | 7 HR | 18 RBI | 2 SB
No one in this class arrived louder. Báez stepped in at Wrigley Field on Aug. 15, hit the first pitch he saw from veteran Matthew Boyd 449 feet to center, and then homered in his next two trips as well. He became the first player ever to homer in his first three career plate appearances. It was not a fluke of a day, either. He had hit 34 homers with 21 steals in 103 games at Triple-A Memphis, leading the level in home runs.
Then the league adjusted. He went 0-for-18 right after the debut and was benched by Aug. 19, recovered to hit .412 over his final 10 games, and had his season ended by an oblique strain on Sept. 18. The .280 ISO, 11.8% barrel rate, and 75.8 mph average bat speed, the fastest in this group, are tantalizing and are what made him a must-pick player for me on our recent Destination Dynasty episode. So is a 33-to-4 strikeout-to-walk ratio and a 35.2% whiff rate. His .303 xwOBA also trails his .335 wOBA, so the results ran a little ahead of the contact.
This is the classic 5×5 versus OBP split. In roto leagues, a corner outfielder who can give you 25 homers and double-digit steals is valuable even with a .230 batting average, and ZiPS projects 14 homers and 25 steals over 123 games in 2027. In OBP leagues, the 3.7% walk rate is a drag. At least his playing time does not seem like an insurmountable hurdle, with Jordan Walker feeling like the only outfield lock for the Cardinals. It also helps that he will spend the winter working on his defense with former St. Louis outfielder Jon Jay. Buying or selling Báez, there really is no wrong way to go.
SS Kaelen Culpepper, 23, Minnesota Twins
Debut: Aug. 7 | 117 AB | .274/.328/.393 | .120 ISO | 21.9% K% | 4.7% BB% | 104 wRC+ | .287 xwOBA | 3 HR | 11 RBI | 1 SB
Culpepper was the first of Minnesota’s three debuts in this group, and the quietest of the lot. The 21st overall pick in 2024 out of Kansas State had hit .271/.367/.478 with 14 homers and 17 steals at Triple-A St. Paul, a standard 15/15 middle-infield profile. His first big-league hit belonged on the highlight reel, taking a 0-2 fastball from Shane Drohan 390 feet into the Brewers bullpen at 100.2 mph.
From there, he was steady more than spectacular. A .274 average and a 104 wRC+ over 33 games is a perfectly fine debut for a 23-year-old shortstop. The concern lies within the expected numbers, though. His .287 xwOBA trails a .320 wOBA, he barreled just 3.4% of his batted balls, and his 87.4 mph average exit velocity ranks near the bottom of this group. The plate discipline numbers are fine but not special: a 21.9% strikeout rate, a 4.7% walk rate and a 26.4% whiff rate. A shoulder contusion and then a hamstring strain that sent him to the injured list on Sept. 16 cut his season short, and he returned only for the final two games.
What Culpepper has that most of this list does not is a clear lane. Rotoworld expects him to be Minnesota’s starting shortstop in 2027, and he keeps his rookie eligibility at 117 at-bats. In 5×5, the value comes from that playing time and a speed and power mix that should look more like his minor-league line than his MLB one, though one stolen base in 33 games is the number to watch. In OBP leagues, the low walk rate caps him. At 157, he’s a hold, a useful middle infielder whose price already reflects the job he can feasibly fill.
2B/LF Michael Arroyo, 21, Seattle Mariners
Debut: Sept. 6 | 35 AB | .371/.439/.514 | .143 ISO | 14.6% K% | 12.2% BB% | 176 wRC+ | .375 xwOBA | 1 HR | 4 RBI | 2 SB
Arroyo found out about his promotion from his best friend. Lazaro Montes, called up a week earlier, phoned him late on a Saturday night, and Arroyo caught a 6 a.m. flight out of El Paso to make Sunday’s game. The Colombian infielder came up as MLB Pipeline’s No. 45 overall prospect after hitting .283 with 18 homers, 81 RBI and 17 steals between Double-A Arkansas and Triple-A Tacoma.
Of every hitter in this group, Arroyo showed the best approach. His 14.6% strikeout rate and 15.7% whiff rate were the lowest of the 12; he walked 12.2% of the time, and his .375 xwOBA says he earned a good chunk of that 176 wRC+. The caveat is the type of contact. A .414 BABIP propped up the batting average, and his 3.3% barrel rate and 88.8 mph average exit velocity point to a hitter who sprays line drives rather than crushes them. That is fine, because that profile is what made him a top-50 prospect in the first place.
The questions for Arroyo are the glove and the depth chart. Cole Young has second base in Seattle, Colt Emerson is the shortstop of the future, and scouts have long wondered where Arroyo fits defensively. The Seattle Times’ Ryan Divish put it simply: his best position is hitter. Left field, where Taylor Ward struggled, is the likeliest landing spot, and that matters in fantasy, since losing second base eligibility would take some shine off. In 5×5, he projects as a high-average bat with mid-teens power and speed. In OBP leagues, his approach makes him one of the best values on this list at 250. A modest buying stance seems like the best way forward this winter.
C Leo Bernal, 22, St. Louis Cardinals
Debut: Sept. 1 | 95 AB | .284/.333/.474 | .189 ISO | 24.5% K% | 6.9% BB% | 124 wRC+ | .347 xwOBA | 5 HR | 21 RBI | 0 SB
If one player on this list has a ranking that has not caught up to his situation, it is Bernal. The Panamanian catcher was a defense-first prospect for most of his climb, winning a minor-league Gold Glove in 2025 and throwing out 27 runners that season. Then the bat arrived at Triple-A Memphis, where he hit .278/.363/.468 with 16 homers and 77 RBI. The Cardinals called him up on Sept. 1, the same weekend Yadier Molina went into the team’s Hall of Fame, and he drove in two runs with his first big-league hit at Dodger Stadium.
He did not slow down. Bernal drove in 12 runs over his first 10 games, a Cardinals rookie record, and finished with five homers and 21 RBI in 24 games. The underlying numbers back him up better than most of the crop here. His 92.6 mph average exit velocity was the best of the 12, his 55.7% hard-hit rate ranked second, and his .347 xwOBA sat right on top of his .351 wOBA. The one hole worth watching is a platoon split, an .899 OPS against righties and .586 against lefties.
The St. Louis Post-Dispatch reported that the Cardinals view Bernal as an “everyday, workhorse catcher” for 2027, and Ivan Herrera, Pedro Pagés and Jimmy Crooks have all been floated as trade candidates. Catchers who hit for power and drive in runs over 120 games are hard to find in 5×5, and he will carry catcher eligibility everywhere. The long-term risk is top prospect Rainiel Rodriguez eventually pushing him toward first base or DH. He’s playing winter ball with Estrellas Orientales in the Dominican now. At 351, he is the clearest buy in this article, but not one to likely hitch your wagon to, especially if the Rodriguez hype does not slow down.
INF Angel Genao, 22, Cleveland Guardians
Debut: Aug. 5 | 127 AB | .213/.281/.291 | .079 ISO | 15.1% K% | 7.9% BB% | 63 wRC+ | .286 xwOBA | 2 HR | 6 RBI | 1 SB
Genao’s first night could not have gone much better. He had four hits against the Mets, the first player in Cleveland franchise history to do it in a debut, including a go-ahead single in the seventh. Chase DeLauter, who came up through the system with him, told reporters Genao was going to be a superstar. He had earned the promotion, hitting .309/.395/.494 with 10 homers and nine steals over 72 games at Triple-A Columbus.
The next 42 games were a different story. Genao hit .213 with two homers and a 63 wRC+, a disappointing end to the season. He was hitting .263 through Sept. 2, then went 7-for-32 to open September and got a day off on Sept. 12 to regroup. The interesting part is that contact quality was not the problem. His 51.9% hard-hit rate ranked third among these 12 hitters, and his .286 xwOBA sat well above his .261 wOBA. The problem was direction. His average launch angle was negative 2.2 degrees, so the hard contact went straight into the ground, and a .240 BABIP did the rest. Bouncing among second, third, and shortstop for a team chasing the AL Central title did not help either.
He finished at 127 at-bats, three shy of the rookie limit, so he keeps his prospect status for 2027. For dynasty purposes, the profile is the bigger problem than the numbers. He is a light-framed switch-hitter whose 5×5 value has to come from batting average, with modest power and speed, and the MLB contact has yet to support that. A swing change that adds some lift would change the whole picture, but that remains to be seen. At 355, he is a hold for deep leagues and a sell anywhere another manager believes his four-hit night is not the final highlight of his career.
OF Bo Davidson, 24, San Francisco Giants
Debut: Sept. 21 | 20 AB | .350/.364/.350 | .000 ISO | 31.8% K% | 4.5% BB% | 100 wRC+ | .266 xwOBA | 0 HR | 1 RBI | 1 SB
Davidson took the long way through to the San Francisco Giants’ outfield. Undrafted out of Caldwell Community College in North Carolina, where his numbers earned him the nickname “JUCO Barry Bonds,” he signed with the Giants in 2023 and kept hitting. This season, he put up a .290/.361/.527 line with 29 homers and 20 steals between Double-A Richmond and Triple-A Sacramento. Before his debut, he told reporters he was “just showing them who Bo is.”
Then he kept doing it. In his first game on Sept. 21, he had a hit, a stolen base and a run, the first Giant to do all three in a debut since Johnny Vergez in 1931. He hit safely in all six games he played. That is about all 22 plate appearances can tell us, though. He did not record an extra-base hit, he struck out 31.8% of the time, and his .266 xwOBA with an 85.2 mph average exit velocity does not support the .350 average. It is a sample too small to grade either way, but certainly with more red flags than green.
The dynasty case is the minor-league power and speed combination on a Giants roster with a crowded but unsettled outfield. Davidson was Rule 5 eligible, so the 40-man spot was coming anyway, and NBC Sports Bay Area expects him to win a starting job somewhere in the outfield long term. He’ll compete with Drew Gilbert, Jonah Cox, Victor Bericoto and others for at-bats. At 24, the ceiling is capped compared with the 21-year-olds above him, but a 25-homer, 15-steal outfielder is a valuable 5×5 piece. At 366, he is a worthwhile deep-league buy.
OF Lazaro Montes, 22, Seattle Mariners
Debut: Sept. 1 | 52 AB | .212/.305/.481 | .269 ISO | 40.7% K% | 11.9% BB% | 120 wRC+ | .313 xwOBA | 4 HR | 11 RBI | 0 SB
Montes said it himself the week before his promotion: “Everybody knows I have the power.” The Cuban slugger hit 38 homers between Double-A and Triple-A, second most in the minors, and wasted no time showing it. In his debut at Fenway Park on Sept. 1, he walked, singled and hit a 407-foot homer, becoming the first Mariner with a multi-hit debut since Ichiro. A week later, he hit a 474-foot, 116.1 mph homer off Cal Quantrill, the longest at T-Mobile Park in the Statcast era.
The power is not the question. His 17.9% barrel rate ranked second in this group, and his .269 ISO and 120 wRC+ say the damage was real when he connected. The question is how often he connects. Montes struck out 40.7% of the time and whiffed on 44.6% of his swings, both the worst marks among these 12 hitters by a wide margin. That is not new, either. He struck out around 30% of the time in the minors, and his in-zone whiff rate was the highest among qualified Triple-A hitters.
In mid-October, MLB.com reported that Seattle had not decided whether Montes opens 2027 as a regular or goes back to Triple-A. That uncertainty, plus the strikeouts, explains his 369 ranking. In 5×5, he is a home run play who could drag your batting average into the basement. In OBP leagues, his 11.9% walk rate softens the blow, and in points leagues that don’t punish strikeouts, he is more interesting still. I’d fade him in batting average leagues and hold in OBP formats, where 35-homer power with walks is hard to replace.
OF Emmanuel Rodriguez, 23, Minnesota Twins
Debut: Sept. 12 | 45 AB | .178/.229/.400 | .222 ISO | 33.3% K% | 6.3% BB% | 69 wRC+ | .354 xwOBA | 2 HR | 5 RBI | 0 SB
Rodriguez has been another Twins prospect whose talent outran his health. He averaged about 59 games a season before 2026, and this year was no different, as surgery on his left thumb in May cost him more than three months. When he played, he did what he always does, hitting .272/.422/.490 with 11 homers in 58 games, mostly at Triple-A. And in his first MLB at-bat, he lined a fastball 111 mph the opposite way for a 420-foot homer. “It was mesmerizing,” he said afterward.
The surface line from there was ugly, though. A .178 average with a 69 wRC+ and a 33.3% strikeout rate. But no one in this group had expected numbers that outran his results by more. His 20.7% barrel rate was the best of the 12, his 48.3% hard-hit rate ranked fourth, and his .354 xwOBA was 84 points higher than his .270 wOBA. The bigger concern is the approach. Twins Daily pointed out that his walk rate fell from 19.1% in Triple-A to 6.3%, while his strikeout rate climbed from 26.4% to 33.3%. Patience was the foundation of his game, and it did not show up in September.
He is out of minor-league options, which means the Twins have to carry him on the Opening Day roster or risk losing him, and the Star Tribune has called him a lock to make the team. Whether that means everyday at-bats depends on Jenkins, Buxton and the rest of a crowded outfield. In 5×5, the batting average risk is pretty concrete. In OBP leagues, his minor-league walk rate makes him one of the more interesting cheap targets on this list. At 391, he is a buy in OBP formats and a hold everywhere else.
1B Yohandy Morales, 25, Washington Nationals
Debut: Sept. 1 | 47 AB | .255/.255/.596 | .340 ISO | 31.9% K% | 0.0% BB% | 124 wRC+ | .317 xwOBA | 4 HR | 10 RBI | 1 SB
Morales is the one name here outside Martin’s top 400, and his season explains why he deserves a look anyway. The 40th overall pick in 2023 out of Miami had become an afterthought in the Nationals system before breaking out at Triple-A Rochester, where he hit .286/.363/.519 with 25 homers and 76 RBI in 104 games, raising his OPS by about 150 points from the year before. When Washington traded away its starting first and third basemen, the at-bats finally opened up.
He made the most of his first night, homering 407 feet off AJ Smith-Shawver and finishing a triple shy of the cycle, and the power held up from there. His .340 ISO was the highest of the 12 hitters in this group, his 62.5% hard-hit rate was the best, and his 15.6% barrel rate ranked third. The obvious problem is he did not draw a single walk in 47 plate appearances. A 31.9% strikeout rate and a 38.1% whiff rate came with it, and his .317 xwOBA says the 124 wRC+ ran a little hot.
RotoWire described his late-season playing time as fairly sporadic, and Andrés Chaparro and Abimelec Ortiz remain in the first base and DH mix, so his 2027 role is unsettled. He turned 25 in October, which limits the upside. But in deep 5×5 leagues, a first baseman with legitimate 25-homer power who costs nothing is worth a roster spot. In OBP leagues, the zero walks are disqualifying until he proves otherwise. I would treat him as a cheap power flier and nothing more.
