It is a belief as old as Yankee Stadium itself. The Yankees cannot afford to take on pitchers who give up a lot of fly balls, as they are destined to give up countless homers within the small confines of the Bronx ballpark. There are numerous horror stories involving starting pitchers who were brought in to stabilize the Yankee rotation and failed because of their proclivity to allow home runs. Because of these failures, the Yankees like to stay away from pitchers who cannot keep the ball on the ground.
Good pitchers come in all shapes and sizes. It is pretty depressing to think that the Yankees should have to just pass up on every pitcher who has a tendency to allow fly balls, especially because they generally have swing and miss stuff. Finding a way for fly ball pitchers to thrive in Yankee Stadium, if possible, would be a major breakthrough for years to come.
First, it is important to understand the science behind fly ball pitcher as most throw four seam fastballs with a high spin rate, which gives their heaters the "rising action" often mentioned by broadcasters. According to Baseball Prospectus, the league-average fastball spins at 2,200 rotations per minute. So a lot of the fly ball pitchers who struggle in Yankee Stadium and other hitter-friendly parks are throwing high spin fastballs that get hit into the seats.
For right-handed starters in the Bronx, the problem is only going to worsen. Yankee Stadium will do no favors to righties who misplace pitches against left-handed hitters. Entering Friday's games, RHP's had thrown over 10,000 fastballs to lefty hitters with spin rates above 2,500 RPM in 2015. Here are a few heatmaps of those pitches, with Pitch F/X data courtesy of Baseball Savant:
The first image simply shows the heatmap of all 10,000 plus pitches. The second shows where hitters swung and missed, and the third shows the location of pitches that were hit for home runs. There isn't much of a discernible pattern for the first map, but right-handed pitchers across the league tend to get burned when they throw their high spin fastballs down and in to lefty hitters. When they keep the ball up and away, they are able to generate swings and misses while keeping hitters frustrated. In theory, fly ball pitchers should be able to do well at Yankee Stadium. They just can't afford to let too many fastballs fall down and in against lefty hitters.
Simply accepting that fly ball pitchers are doomed to mediocrity at Yankee Stadium is tough to do. If there was an abundance of ground ball generating southpaws like Dallas Keuchel or Jaime Garcia, the Yankees rotation would be fine. Unfortunately, those types of pitchers are very difficult to find. If a fly ball pitcher happens to be able to command his fastball well enough to avoid mistakes down and in, the Yankees should consider taking a flyer on him. Finding a way to develop fly ball pitchers for Yankee Stadium would open up a new range of possibilities for the front office. Knowing how hard it is for pitchers in the Bronx, they should certainly be looking for any help they can get.