Justin Verlander Returns to Astros

Justin Verlander’s tenure in the Big Apple didn’t last very long, as he was shipped back to Houston, where he spent the last four years and a month, during Tuesday’s always chaotic trade deadline. With excellent results once again this season, how might the park switch affect his performance? Let’s consult the park factors to find out.

We’re back to comparing clean sweeps! This actually isn’t very unexpected, as Minute Maid Park (MMP) has had a reputation as a hitter friendly park, particularly for home runs, while Citi has been known as a pitcher’s park. Of course, that MMP reputation isn’t exactly true, so the gaps here are perhaps smaller than expected. Let’s dive into the individual factors.

We begin with the hit type factors and find that Citi takes the cake across the board. While MMP suppressed both singles and doubles, Citi simply did it better. As a fly ball pitcher throughout the vast majority of his career, Verlander has posted a BABIP no higher than .272 every season since 2015. His career mark stands at .278 and he’s come in at .258 this year. The odds are his BABIP does rise over the rest of the season, but it’ll be difficult to tease out the effects of MMP being slightly less hit suppressive versus good old regression. While the Mets pitching staff has posted a slightly lower BABIP than the Astros, the latter ranks seventh in UZR/150 versus just 26th for the former, with a similar gap seen in Def. So it’s fair to say that the Astros defense is probably better than the Mets and should be able to offset any difference in park effects. That said, I’d still bet on his BABIP going up.

We see a large gap in triples factors, but given the infrequency of the hit type, it shouldn’t have much of an impact. Then again, as a fly ball pitcher, this factor comparison might impact him more than most, but it would still be minuscule. The home run factor difference is meaningful, but probably not as large as I, and I’m sure most of you, expected. MMP is certainly a good place for home runs, but not a great place, while Citi was a below average park for home runs, but not significantly.

After posting single digit HR/FB rates every season from 2007 to 2015, Verlander hit a home run rough spot, posting marks just into double digits from 2016 to 2018, before posting his highest mark yet in the mid-teens in 2019. Then last year he was back to just 6.2% and he sits at just 8% this year. His career mark is only 8.9%, so whatever he’s doing, he clearly owns HR/FB rate suppression skills. I would still bet on that rising in a more home run friendly park, but given a small sample size of fly balls, it’s anyone’s guess what he’ll do in Houston.

Moving along to the batted ball type factors, we find that MMP has been neutral for grounders, but suppressed fly balls, while the opposite has been true at Citi. Verlander posted his highest career FB% while playing half his games in Houston back in 2018, so I doubt the park switch is going to increase his GB% and reduce his FB%. The next two batted ball type factors are the ones that should impact performance — LD and IFFB. Both favor Citi, which could result in an increase in line drives allowed and reduction in pop-ups induced. Those effects should be factored into the hit type factors already, but do help explain what’s driving some of the discrepancy in those factors.

Finally, we end up with the summary run scoring factors, FIP and Basic. Not surprisingly, MMP is less pitcher friendly, but perhaps surprisingly, they actually are slightly pitcher friendly and not actually hitter’s parks. The difference in HR park factors probably explains most of why the FIP factors are fairly close, but the Basic factors are further apart.

It’s pretty clear that strictly from a home park perspective, this is a marginally negative move for Verlander. However, it appears the Astros are running out a better fielding unit, while the Astros also have had the better offense. Although the two teams’ wOBA marks are fairly similar, the Astros have scored 4.77 runs per game, while the Mets have only scored 4.45 runs per game. I’m guessing the Astros have hit much better with runners on base and/or scoring position to score that many more runs per game, despite a wOBA only a couple of points higher.

So does the better defense and offensive support offset the more hitter friendly park? I don’t know! But it seems close enough that the move shouldn’t impact Verlander’s rest of season fantasy value expectation much.