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Yaz We (Maybe?) Can: Mike Yastrzemski Season Review

Yaz took a step back from his MVP-vote highs of 2020, but still posted positive value for the Giants this season.

San Francisco Giants v San Diego Padres Photo by Denis Poroy/Getty Images

Sometimes, writers have to disclose paid sponsorships, or secret affinities for hometown players. In the interest of full transparency, I have to disclose my own soft spot for Mike Yastrzemski: we share a nickname (Yaz). This shared name operates like a powerful +10.0 WAR; whatever Yaz’s stats might actually be, he’s always going to be an MVP in my heart. Nobody said I had to be unbiased!

Also my username for my fantasy baseball team this season was Yaz We Can, which is a pun I’m still very proud of and felt the need to share here. (I finished sixth of eight, but who’s counting?)

Putting aside Yaz’s spectacular choice of nickname, we should turn to his actual on-field performance. For context, as most know, Yastrzemski came over to the San Francisco Giants from the Baltimore Orioles in a 1-to-1 swap of minor league players: the Giants sent minor league pitcher Tyler Herb and received Yastrzemski in return. Herb is no longer with the Orioles organization, while Yastrzemski has put up 7.7 bWAR with the Giants... well, we can say who won that trade, I suppose.

2021 Review

Yastrzemski entered this season with major expectations. He finished 8th in NL MVP voting in the pandemic-shortened 2020 season, putting up a .297/.400/.568 slash in 54 games with 10 HR, good for a 159 wRC+ and 2.6 bWAR. That WAR ranked 10th in baseball among position players, so you can get a sense of just how spectacular Yastrzemski was.

In 2021, however, Yastrzemski fell back to Earth with a bit of a thump. He slashed .224/.311/.457 in 139 games with 25 HR, coming out to a 106 wRC+ and 2.5 bWAR. The defense remained positive (+0.3 dWAR), and he was rewarded with a Gold Glove nomination, but the bat was just about average, though he was second on the Giants for home runs.

So, what happened? In his spectacular 2020 season, Yastrzemski had basically no difference when he faced RHP or LHP pitchers, posting a 156 wRC+ and 165 wRC+ respectively. Essentially, he was massively above average no matter who he was facing. That illusion was shattered in 2021, with him posting a 46 wRC+ against LHP and 126 wRC+ against righties. He was basically unplayable when the Giants faced LHP. Against LHP in 2021, Yastrzemski posted a .170/.254/.259 line. This is bizarre, because in 2020 Yastrzemski posted a .284/.385/.612 slash against lefties for that 165 wRC+, and even in 2019 slashed .329/.382/.561 for a 145 wRC+. He used to not only be good against left-handers, but elite: his 154 wRC+ against LHP across 2019-2020 is the basically the equivalent of Fernando Tatis Jr.’s 2021 season (156 wRC+). So how do you go from Tatis Jr. to Cody Bellinger (48 wRC+ in 2021)?

It’s actually not entirely clear what changed. But maybe the pitch charts have part of the story: looking at Yaz’s zone chart, he really struggled on pitches down and away (wOBA means weighted on-base average, so the higher, the better: it scales with OBP, so the evaluation is the same), a trend that didn’t necessarily hold true when looking at 2019-2020.

And lefties tend to throw there.

It’s a bit of a chicken-and-egg question. Is Yaz struggling on those pitches because he can’t handle that type in particular and lefties just happen to throw there, or is it because he can’t handle lefties and that’s where the majority of lefties throw those pitches?

Maybe it’s a bit of both, but he was significantly better against those pitches from righties vs. lefties, as seen below:

So there’s something going on here with the way he faces LHP in particular. The ball breaks away from RHB when thrown by a lefty, and there’s also a different arm slot. It’s possible he’s picking up the motion or the spin significantly less than he usually does.

There’s more investigation to be done here, and I plan to write a future article with a deeper dive into what exactly went wrong for Yaz in the 2021 season. But in totality, while he did put up an above-average wRC+ of 106, he didn’t perform to the potential we all know he is capable of. However, he did pair that league-average bat with good defense, worth +6 OAA, making him an overall valuable contributor. His 2.5 bWAR gives you a sense: he’s a solid starter, even if he didn’t quite reach his All-Star potential.

Role in 2022

If Yaz can figure out left-handers, he’ll retain his role as the everyday right fielder for the Giants with occasional appearances in center and left as needed. If his struggles against lefties seem more permanent, he might have to become the right side of a platoon with Darin Ruf, who hits lefties better than he does righties.

The Giants aren’t done with free agency signings yet either, and signing a RHB like Seiya Suzuki or Kris Bryant might also determine Yaz’s playing time. The Giants tendered a 2022 contract to Yaz, but the sides had not yet agreed on terms before the lockout began, making arbitration a possibility in the spring if the two sides can’t agree.



How do you grade Mike Yastrzemski’s 2021 season?

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