kWAR and gWAR Midseason Update: Risers and Fallers

The kWAR/gWAR midseason update is here.

During the 2020 pandemic lockdown, I had the opportunity to create the statistics kWAR and gWAR, WAR statistics based around ERA estimators, kwERA, and GBkwERA. I wrote a season preview about some potential turnaround candidates or even players who can reach a new level that you can read here. I have updated the kWAR and gWAR sheets to include statistics from before the All-Star break. To fully understand the statistic and what it does, you can read the update back in 2020 here. It’s meant to be predictive statistics, so it will help project future performance which can make it useful to fantasy managers everywhere. With that said, I will discuss six players whose stock should either rise or fall based on estimations from kWAR and gWAR. I should note that a Toronto pitcher is in here and that park factoring for Toronto pitchers did not factor in the change in ballpark midway through the season. I should also note that these statistics do not take into account a change in spin rates since the crackdown. 




Risers were chosen based on the difference between their kWAR and gWAR values being higher than their fWAR values. To qualify as a riser both their kWAR and gWAR had to be at least one win higher than their fWAR. Of the 755 possible pitchers to throw a pitch this year, only 12 qualified for this. Of those 12, here are the three most intriguing pitchers in my opinion to keep an eye on in fantasy trades. 

Robbie Ray


Robbie Ray has discovered himself in the past few weeks. But kWAR and gWAR believe he should have been this good the whole time. He enters the second half of the season with a 3.09 ERA but a 3.94 FIP. Admittedly, if you play in FIP leagues then Ray is a bit of a gamble given his problems with the home run have plagued him his whole career. However, his 3.13 kwERA and 3.19 GBkwERA are much more reflective of the pitcher he’s been so far this season. No player has underperformed their kWAR and gWAR more than Robbie Ray. His 3.1 kWAR and 3.0 gWAR are good for 12th in all of baseball. His fWAR of 1.5 is good for 57th. It’s hard to imagine the Ray gets that much better though, right? 

All of his peripheral statistics are in line with his ERA outside of his FIP which is why it’s so low. Ray does get hammered when he gives up contact, hence the home run issue, but he does have a solid 41% ground ball rate. Pair that with a career-best 6.2% walk rate this year, it’s not unfathomable that Ray could finish the year inside the top 10 in either kWAR or gWAR. Ray has always had this kind of potential if he could limit the walks, and yes a walk rate as low as his does scream potential anomaly and could ultimately lead to regression—but his walk rate held stable at six percent in June and so far in July. This could be the breakout year again for Robbie Ray


Adbert Alzolay


The Cubs right-hander has seen his fair share of troubles so far this year. Alzolay enters the second half with a 4.66 ERA but even worse 5.10 FIP. That’s fueled his staggeringly low .2 fWAR across 77 innings. Frankly, it doesn’t take a genius to tell you that a 25% HR/FB ratio is unsustainable and he should be able to move past that. But even then, Alzolay does some things that are worth highlighting. In both 2019 and 2020, Alzolay had a walk rate above 14%. This year, he’s cut that to just seven. A huge step forward for him. He still strikes hitters out a respectable 25.7% clip as well. Both of those things have given him a 3.98 kwERA. Factor in his ground ball rate of 44%, his GBkwERA is 3.97. Those are some pretty stark differences between his ERA and FIP. 

Alzolay was second in the differential of gWAR behind Robbie Ray, and third in kWAR differential behind Ray and Mike Foltnewicyz. His 1.6 kWAR and 1.4 gWAR point to a rising young pitcher but his results haven’t lined up with that. Alzolay is a slider heavy pitcher and while his slider appears to be a plus pitch, the Cubs have tinkered with his pitch mix a lot since his debut and that could be causing some issues for Alzolay. His fastball gets hammered probably more from command than the movement profile of the pitch. His sinker gets a lot of movement but he could adjust the spin direction of the pitch to try and get more side spin to help induce more groundballs. Alzolay just needs to figure out his pitch mix, but the signs of a great pitcher are there. 


Raisel Iglesias


Few relievers have gotten burned quite as Raisel Iglesias did early in the season. Yet, he’s turned it around in the past few months and that is the pitcher you can expect to see going forward. Iglesias is the bright spot along with Shohei Ohtani in an otherwise, dreadful Angels pitching staff. Iglesias has a 3.46 ERA and 3.52 FIP. He has gotten burned by the same thing that has burned Alzolay, a 25% HR/FB ratio. Despite that though, Iglesias is inducing the highest groundball rate since his rookie year. He also has the best K-BB% of his career at 35%. 

For Iglesias, it’s just that simple, he will get burned now and again by the home run, like all relief pitchers but there’s no way his current rate will last. He’s doing things the best he’s ever done them before. His kWAR and gWAR of 2.0 rank third among relievers so far this year. If there is an opportunity to get a pitcher who not only gives you saves, but a lot of strikeouts and should see his ERA start to dwindle, fantasy managers should jump at it. If you’re in the middle of a potential push in your fantasy championship, Iglesias is a good trade deadline acquisition. 




Fallers were a bit more difficult to establish—only one pitcher had underperformed their fWAR by more than one win in both kWAR and gWAR, and that pitcher is qualified. The other two candidates were chosen because I think there are interesting cases to be made for both. They both have overperformed their metrics to the point that it is possible to expect some sort of regression. Here are three candidates to look out for in the second half of the season. 


Nathan Eovaldi


There isn’t a candidate more painful to write about than Nathan Eovaldi. I wrote about him possibly getting better in the season preview, and now I have to write about some concerning trends this time around. Eovaldi has a 3.66 ERA but a 2.60 FIP. He just doesn’t give up home runs, it’s a weird ability that has gone his way this season. Now, the rest of his peripherals are closer to his ERA—so why should the fact that his FIP is crazy low matter that much? Well, if the home runs start to come, the ERA is going to skyrocket. 

Eovaldi’s groundball rate is the lowest since his days in Miami. In a year that is seeing more strikeouts than ever, Eovaldi’s strikeout rate is closer in line with where he was in 2018. Those are concerning numbers reflected in his stark 2.0 kWAR and gWAR vs his 3.4 fWAR. Eovaldi gives up a fair amount of contact and his 1.23 WHIP and .334 BABIP reflect that. The glimmer of light is that Eovaldi’s CSW is the highest it’s ever been in his career, it’s just not translating to strikeouts. Something has to give in either direction. He’s either going to start getting burned by the home run ball, or the strikeouts will start to come. I hope for his sake, it’s the latter option. 


Trevor Rogers


Admittedly, this choice might be a bit harsh. Rogers is in the middle of a fantastic rookie campaign and there’s not a lot of data about him as a major league pitcher but still, Rogers was underperforming his fWAR by at least half a win in kWAR and gWAR. Rogers does have a 30% strikeout rate which is phenomenal, and his walk rate has fallen 2% from his small sample size last year, he’s getting a lot fewer groundballs. Now again, a 42% clip is roughly average, but it fell about 7% from his small sample last year. His kwERA and GBkwERA are the highest peripheral statistics he offers but they are closer to his SIERA value than his ERA value. 

I think Rogers is an interesting choice because he represents the issue with data in small samples. Is Rogers a pitcher who can consistently overperform his peripheral statistics? He has a very low HR/FB% now but that’s not always a stable and reliable metric. Is he just in a fluky ground ball year and he’s closer to an above-average ground ball generator? Evaluating prospects and rookies can be difficult, which means to say I’m using Trevor Rogers as an example to say that it’s possible he regresses but these statistics on rookies are not full proof and a large sample of data is needed before making a more informed stance. With that said, I think you can expect some regression from Rogers, but how much I do not know. 


Taijuan Walker


The Mets All-Star pitcher Taijuan Walker is another interesting case. His ERA being well below three is a peculiar case. All of Walker’s peripheral statistics are well above his ERA and FIP. Like the other two pitchers, a large part of that stems from his low HR/FB% that is well below his career norm. Walker also generates a well below average ground ball rate at 39% cause a lot of concerns. His kwERA and GBkwERA are both over 4.20 and his SIERA is above four as well. He has a slightly above average walk rate and a slightly above average strikeout rate which is a good sign. 

Part of those numbers are fueled by a tough April in regards to the walks and groundballs but the numbers haven’t dramatically improved in the groundball department as the year goes on. He has improved his command throughout the year and so that could bring the numbers down. Walker is in the wait-and-see category but he’s been giving up some home runs recently so the trends might not be working in his favor. If Walker can keep his walk rate around 6% then the issues might be coming down but the home run issue remains then Walker will have a tough second half. 

Get ready for the second half of baseball by enjoying the full leaderboard of kWAR and gWAR here.


Photo from Rich von Biberstein, Mark Alberti, Cliff Welch, Gregory Fisher, Jeff Robinson/Icon Sportswire | Design by Quincey Dong (@threerundong on Twitter)

Max Greenfield

Former Intern for the Washington Nationals, now a Going Deep Writer analyzing the next possible breakout pitcher.

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