Sonny Gray may have a Yankee Stadium problem

Sonny Gray knows how to pitch. The right-hander stands out as a cerebral starter on the mound. Some criticize him for nibbling instead of challenging batters outright. That, however, isn’t a fair assessment. Gray doesn’t have overwhelming stuff, but he can keep a lineup guessing. He works the corners because that brought him success.

A valid shortcoming, however, presents itself with his newfound propensity to give up home runs. Heralded as a groundball pitcher, Gray seemingly has struggled to keep the ball in the park since joining the Yankees. A closer look at the numbers confirm this observation.

Gray’s numbers declined across the board since the trade. Some of those numbers have a less significant disparity than others. For example, his strikeout rate has basically held constant. The red flags, however, pop up when it comes to the long ball. In short, Gray became homer-prone upon joining the Yankees.

We know that he’s struggled to keep the ball in the park. The more interesting question, though, is why? When a pitcher experiences a spike in his home run rate, two culprits come to mind. First there’s the matter of location. Sometimes a starter begins to miss spots leading to the barrage of homers.

Could that explain Gray’s woes? A comparison of his heatmaps suggests otherwise. The first image below shows his pitching profile when he was still a member of the Athletics.

Now compare that to his heatmap since joining the Yankees:

Those look fairly similar to me. The only noticeable change appears in the center of the plot. Gray hasn’t challenged as many batters right down the middle since donning the pinstripes. That, however, could just be a sample size issue. The rest of the map seems perfectly in order.

When location fails to provide an adequate answer for a home run spike, mechanics comes to mind. Is it possible that Gray experienced a breakdown in form upon arriving in the Bronx? The evidence again suggests otherwise.

Gray’s release points have been stable all season. Very little separation exists. That leads one to believe that his mechanics have been consistent. He hasn’t changed or altered his pitching style by any noticeable means.

If that’s not the case, then what explains his home run revolution? Could it instead be a matter of ball parks? That appears more likely. Across 28.2 innings at Yankee Stadium, Gray owns a 5.65 ERA with an astronomical 6.22 FIP. He also maintains a sky-high 2.5 HR/9 at home. On the road, however, he’s pitched to a 2.21 ERA (3.81 FIP) over 36.2 innings. His HR/9 drops down to 0.70.

It’s safe to say that this is the problem. Gray pitched in a spacious park with the A’s. He now calls the bandbox of Yankee Stadium — and the rest of the AL East — his home. Fly balls that would be caught for outs in Oakland land in the right field seats in the Bronx. He has a much smaller margin of error to work with now.

This trend proves problematic considering the Yankees’ potential playoff standing. Should they advance beyond the Wild Card round, having Gray on the mound at Yankee Stadium makes for a nerve-wracking experience. On the road, however, he’s as advertised — better than one expected, even. I’m confident in Gray’s ability to adjust, considering his pitching IQ. That may not come this season though, which could make for a precarious playoff run.