Is Mike Yastrzemski Undervalued?

How does the Giants outfielder's skill set compare to his current late-round ADP? Matt Wallach breaks down the numbers.

When remembering some of the more pleasant surprises from the 2019 season, Mike Yastrzemski should be towards the top of any list. Previously most notable for his last name and family history, Yastrzemski came into his own and established himself at the ripe age of 28 to become, perhaps, the best hitter on the Giants. His home run in his first game at Fenway Park, where his grandfather put up a Hall of Fame career and in which he played all 23 of his seasons, was one of the coolest moments of the season. Yastrzemski was more than just a nice story, though, because he was actually very good in his rookie season. His .272/.334/.518 slash line was extremely strong and good enough for a 121 wRC+, and his 21 home runs in just 107 games tied for the Giants team lead with Kevin Pillar.

As we quickly approach the 2020 season though, we have to ask: Can Yastrzemski do it again? Was he a flash in the pan? What should our expectations be for him in 2020? His current draft position in three major formats seems to suggest more flash-in-the-pan than future contributor:

According to these platforms, Yastrzemski is a near-final round of the draft selection, or possibly an undrafted option in twelve-team leagues, which seems odd to me considering his strong 2019 performance. But fine; ADP is not the be-all-end-all, and there are flaws in using ADP to run a fantasy draft. So let’s then turn to a usually more reliable set of data: the projections. Maybe his current ADP hasn’t yet considered the projections. Let’s take a look at what some of the more popular projection systems think of Yastrzemski going into 2020 compared to his 2019 season:

Mike Yastrzemski – Projections

Based on the projections, it looks like his ADP is probably justified, as he projects to be a roughly league-average hitter without an outstanding batting average, on-base percentage, or extremely high home run or RBI totals. There are plenty of reasons for the projections being low on Yastrzemski. The most obvious of which is that he’ll be 30 years old by the end of the 2020 season and he doesn’t have a long track record of Major League success. The odds of him being a particularly relevant hitter for long are clearly against him, and there’s a good reason for that. There aren’t a lot of precedents for success with players with a history like Yastrzemski’s. The projections are usually a good starting point, but when I look deeper into Yastrzemski’s profile, I see some things that the projections may not be taking into consideration. After taking a closer look, I feel like his 2019 season was not a fluke. While I’m not going to project him for the next five years and say that he’ll continue to be solid after those five years (aging curves get everybody, eventually), I simply think he’ll produce good value in 2020. I believe that we are not giving Yastrzemski enough credit for what he did in 2019 and that he is being extremely undervalued and underrated going into this season.

Now it may seem optimistic to assume that Yastrzemski will hit 20 or more home runs again in 2020. Not only was the ball juiced in 2019, resulting in an extreme offensive environment, but throughout his minor league career, Yastrzemski wasn’t exactly a home run hitter. Only in 2019 did he see a jump in his home run power, and that could easily be written off as Triple-A now using the Major League ball. In 2018, he hit just 10 home runs in Double-A and Triple-A, and it wasn’t much better than that in years prior. On top of that, his home ballpark is one of the most limiting for hitters. While Oracle Park’s dimensions are changing in 2020, which will shorten the distance to straightaway center field, the left-center gap, and the right-center gap known as Triples Alley, it is still likely to play as a more pitcher-friendly park. While some of these factors may turn some off, as fantasy baseball players may prefer some stability in the later rounds, what Yastrzemski managed to do in 2019 in one of the worst places to hit as a batter was really impressive.

While Oracle Park is limiting to most, it wasn’t limiting to Yastrzemski in 2019. Perhaps some of that can be attributed to the juiced ball, but looking closer, Yastrzemski just hits the ball well. First off, consider his spray chart:


Looking just at his fly balls and line drives overlayed onto Oracle Park, it doesn’t look like he hit many cheapies that just scraped over the wall, which would have been outs without a juiced ball. There are also some deep flies that would have likely have gone out elsewhere, but for the most part, those look like pretty impressive homers. Want some visual proof? Take a look at these shots:

And then this one, where Bryce Harper doesn’t even bother to give it a courtesy chase:

These are quite impressive shots, and these types of home runs are rare for Oracle Park. And while his average home run distance isn’t the most impressive at 406 feet, it is still very good, as it was still 65th best out of 272 hitters in baseball with at least 300 plate appearances in 2019, nearly identical to some notable hitters like Nolan Arenado, Shohei Ohtani, Josh Donaldson, and Cody Bellinger. But what is more encouraging is that his average fly ball distance ranked much higher. This time, his 340 feet in average fly ball distance puts him at 34th, again among hitters with at least 300 plate appearances, right in line with the likes of Arenado, Ohtani, Donaldson, and Bellinger. This is notable, because while average home run distance does have its uses, average fly ball distance correlates better to HR/FB rate, ISO, wOBA, and xwOBA than most metrics. While the juiced ball certainly didn’t hurt him, I don’t think the juiced ball is enough on its own to explain Yastrzemski’s strong power showing

So, the question then becomes: How did he get this power? The juiced ball alone is clearly not the answer, so there has to be something deeper in his profile to explain his power surge. After all, Statcast seemed to believe his power output was legitimate in 2019, with his .510 xSLG very much in line with his .518 actual SLG, so he must be doing something right. First off, his batted-ball distribution is solid. It’s nothing special, and it has room to improve, but there’s nothing inherently bad about it. His 36.2% ground ball rate is way less than the 45.4% league average, he hits fly balls at an above-league average rate (29.1% compared to 22.0%), and while he doesn’t hit as many line-drives as the league average, it’s not too far off at 23.9% compared to 25.5%. Again, not perfect, and he would be better off by cutting down on his 10.8% pop-up rate, but this is a nice, solid foundation for success. I looked for all the hitters from 2019 with at least 300 plate appearances who hit ground balls at a rate lower than 38%, and who also hit fly balls at a 27.5% or better clip, and also hit line-drives at a rate better than 23.0%, to try and find some comparisons and contextualize Yastrzemski’s 2019 season. The results of that query returned 45 hitters, ranging from Mike Trout to Curtis Granderson. This query was just to try and get a group of hitters with a more desirable batted-ball distribution, not necessarily to find the best hitters.

Filtering some more to look for hitters who not only distribute their batted-balls more optimally, but also actually hit the ball well, I looked for hitters within this group of 45 that have similar launch angles, exit velocities, and barrel rates to Yastrzemski. Yastrzemski does hit the ball well, which is part of the reason why Statcast seemed to support his power breakout last season. Here’s a summary of how he compares to the league average in some key batted-ball rates:

Yastrzemski vs. League Average – Notable Statcast Metrics

While his average exit velocity doesn’t seem super impressive, as I’ll show later on and is partly teased by his standout barrel and hard-hit rates, Yastrzemski hits line-drives and fly balls extremely well, which doesn’t necessarily show up in his overall average exit velocity, but more on that later. Knowing Yastrzemski’s notable Statcast metrics, I could further filter down my original group of 45 hitters using some benchmarks. The results of this query netted sixteen different hitters:

LA >= 16.5, EV >= 87.5, BRL/BBE% >= 10.0

Overall, this is a pretty nice group of hitters. I also want to highlight Yastrzemski’s average launch angle. If prior research is to be believed, the “ideal” launch angle is somewhere around nineteen degrees. A nineteen-degree launch angle is one of the best when it comes to wOBA, AVG, and HR%, so Yastrzemski certainly seems to be in good shape here. Also, remember how he didn’t hit home runs before 2019? While we don’t have access to minor league launch angles, it certainly seems as if Yastrzemski made some sort of adjustment with his swing that was geared towards him getting more lift. That should further dispel the belief that his power jump was mostly due to a juiced ball, but rather a mechanical adjustment that didn’t show up in public circles until he was already well into his rookie season.

Getting back to our group of sixteen hitters though, we can still filter this down further, this time looking at hard-hit rate, while also adding in xSLG. The goal this time is to get a final list of power comparisons for Yastrzemski. Looking at hitters from this group with a hard-hit rate of at least 40%, while also having an xSLG mark greater than .500 returns us with our final group, this time with eleven hitters:

Hard-Hit% >= 40.0, xSLG >= .500

No offense to hitters like Renato Nunez and Matt Adams, but this is a much more solid group of hitters now. Yastrzemski is in the most elite company here, and while the rest of Yastrzemski’s game is what pushes him away from these hitters overall, the way he hits the ball proves to me at least, that his power eruption in 2019 was not a fluke. In 2019, he hit for power at a rate that compares especially well to hitters like Eugenio Suarez, Brandon Lowe, Mike Moustakas, and Edwin Encarnacion, but Yastrzemski is the one that’s being left to the final couple rounds, or possibly undrafted. Now that’s some crazy stuff to me.

But wait, there’s more! Despite sounding like I belong on an infomercial, I did tease something notable about his average exit velocity, and now it’s time to bring that up for real. To get right to it, I believe Yastrzemski’s average exit velocity of 88.7 mph is actually underrating his exit velocity abilities. I think it’s a good idea to break out exit velocities into buckets for each batted-ball type. After all, how hard a hitter hits his line drives is more important to me than how hard he may hit his ground balls, as line drives lead to more hits. So, let’s run this exercise with Yastrzemski and compare him to the league average:

Yastrzemski vs. Average – EV Splits

These averages come from hitters with at least 300 plate appearances in 2019, so if we were to include all hitters, I’m sure those averages would drop somewhat, but as you can see, Yastrzemski does hit his ground balls weaker than the league average, while he hits his line drives and fly balls harder than the league average. Yastrzemski doesn’t even hit ground balls at a high rate, as I showed earlier, so I’m not overly concerned that he hits those weakly, because he hits the better batted-ball types much harder. So, combining Yastrzemski’s average exit velocity on line drives and fly balls should provide a clearer picture. The average exit velocity on line drives and fly balls is already a much-used statistic, and like average fly ball distance, correlates extremely well to HR/FB rate, ISO, wOBA, and xwOBA. We already saw that Yastrzemski’s average fly ball distance stands out, but how about his average exit velocity on fly balls and liners? He comes out with a 94.7 mph mark, which puts him 78th, in line with other hitters like Paul Goldschmidt (94.5 mph), Mookie Betts (94.2 mph), and Xander Bogaerts (94.1 mph), among other notable hitters, and ahead of the 92.8 mph league average. However, if we filter to look only at hitters with a ground ball rate of less than 40%, Yastrzemski jumps to 24th. Filtering down to look at those hitters lets me look at hitters who already do two important things well: Keep the ball off the ground, and hit the ball hard in the air. This also eliminates hitters who may hit the ball hard in the air, but already hit too many, or more than desirable amounts of ground balls, so they don’t get to benefit from their solid exit velocity numbers as often as the hitters in this group.

We can go even further by looking at the hitters with the biggest differences from combined exit velocity on line drives and fly balls to their overall average exit velocity. Keeping the same restriction of looking only at hitters with ground ball rates lower than 40%, Yastrzemski’s 6 mph difference is the 12th largest. Filtering that down further to only look at hitters who already have a better-than-average exit velocity, we get these results:


Yastrzemski moves up to the sixth spot using these criteria. Overall, Yastrzemski’s average exit velocity doesn’t look very impressive, but when grounders get ignored, Yastrzemski does look a lot better, and I am more concerned with how hard a hitter hits line drives and fly balls than I am about how hard he hits his ground balls.

Knowing what I now know about Yastrzemski, and seeing how his results compared to his ADP, I believe he is being underrated going into drafts in 2020. It’s an easy thing to do, as all the variables seem to be against him: He’s already old for a player entering his sophomore season, he doesn’t have a long track record of success in the majors or minors, and his home ballpark is one of the worst to hit in. However, he managed to work around what was thrown at him last season and was a pleasant surprise, as he was among the best hitters on the Giants in 2019. As I looked deeper into Yastrzemski’s profile, I saw more and more that I liked. He has a good foundation with his solid batted-ball distribution, and he combines that with an average launch angle among the best in terms of expected results, and he hits the ball hard. I didn’t even touch upon how well he sprays the ball. Spoiler alert: He also does that pretty well, as he is one of the best left-handed hitters on batted-balls that go to the opposite field, and spray angle should not be ignored when evaluating hitter performance. Yastrzemski still isn’t a perfect player by any means, and there are batting average concerns, notably because he doesn’t walk very much, and he strikes out more than we’d like to see. However, I still like Yastrzemski a lot, and I think he should be drafted much higher than he currently is.

Photo by Larry Placido/Icon Sportswire | Adapted by Michael Packard (@designpack on Instagram and Twitter)

Matt Wallach

Matt studied accounting at UAlbany, is a Yankee fan, and writes for Pitcher List and Rotoballer where he can work with even more numbers to analyze baseball players, which is a lot more fun.

2 responses to “Is Mike Yastrzemski Undervalued?”

  1. Harry Lime says:

    Okay, okay, he’s on my list!!! Good work Matt.

  2. Carlos Baerga says:

    Low EV on GB with a strong pull GB split and higher than average PU% = low BABIP / low average. I see him hitting .230-.240 assuming his profile stays the same. Yes he could hit 20-25 HR but with high K and modest walk rates I don’t see much upside outside of another year with extreme batted ball luck like he saw in 2019.

Leave a Reply

Your email address will not be published. Required fields are marked *

Account / Login