Sonny Gray Switches Coasts

It was a relatively unexciting trade deadline as fewer big names switched uniforms than usual. No, I don’t have any actual data to back that up, but I feel like I’m probably right. Anyhow, one of the bigger names to switch teams was Sonny Gray, as he departs the West coast for the East, joining the New York Yankees. Let’s analyze the park factors, the team defenses, and offensive support to help determine how this affects his value over the rest of the season.

Obviously, no one really needed to check the park factors to confidently say that Yankee Stadium is much more hitter friendly than the Oakland Coliseum. This year, the former has boosted run scoring by 7%, while the latter has suppressed it by 5%. It’s a meaningful swing. But what’s actually driving the disparity in run scoring?

Surprisingly, Oakland actually increased line drives, while Yankee Stadium has reduced them. No, I’m not sure specifically what is causing such factors in these parks and how much of it could be noise, but it’s still worth noting as a potential benefit. So that clearly isn’t what has helped fuel Yankee Stadium’s hitter friendliness. Either is strikeout rate, which is boosted in Yankee Stadium and suppressed in Oakland.

Finally we get to two park factors that favor Oakland. The park has reduced walk rate, while Yankee Stadium has boosted it slightly. In addition, Oakland has reduced singles, or as I like to equate it to, BABIP, by 5%, while Yankee Stadium is almost neutral. However, Yankee Stadium offers a big advantage in doubles and triples, the latter seemingly being a rarity at the park.

Then, of course, we get to the most important disparity that most could have guessed — home runs. The new Yankee Stadium has been one of the top home run parks in baseball since it opened. That differs from the Oakland Coliseum that has consistently been one of the most difficult parks to hit a homer in. And there’s essentially what is driving the difference in run scoring between the two parks.

The good news for Gray owners is that he has always been an extreme ground ball pitcher. This year he has allowed the lowest fly ball rate of his career, so even if his HR/FB rate does rise, it won’t dramatically affect his ERA like it would be an extreme fly baller. That said, clearly the park switch alone is a negative here.

From a defensive support perspective, this is a big win for Gray. He leaves a team that ranked dead last, by a wide margin, in UZR/150 to the eighth best. And while the Yankees infield defense is nothing special, Matt Chapman has been the only positive defender in Oakland. And that outfield has been brutal.

Last is the differences in offense. The Athletics have scored about 4.26 runs per game for the season, versus the Yankees that have scored more than a run more at 5.29. Over the last 30 days, though, the two teams have actually posted identical wOBA marks and nearly the same number of runs per game. Still, I’d bet on the Yankees being the better offense the rest of the way.

So Gray loses with the park switch, but gains in defensive and offensive support. Since his .285 BABIP is already below average, I doubt the defense suppresses it further, so his ERA is at risk of rising if his HR/FB rate heads upward. But, he could win an extra game or two due to the improved run support, and the strong Yankees bullpen. Overall, I’d say this was rather neutral for his fantasy value.