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Should the Yankees panic over Luis Severino?

The team’s ace has had a horrible July, but is there real cause for concern?

Kansas City Royals v New York Yankees Photo by Mike Stobe/Getty Images

A month ago, Luis Severino looked like a man on the verge of putting away a Cy Young campaign for good. The flamethrowing righty was the best pitcher in the American League, had a legitimate case to start the All-Star Game, and was pacing the field of excellent AL pitchers. Since then, everything’s gone wrong:

Severino went from the class of the American League to looking like the shellshocked sophomore he was in the 2016 season. He shut out the Red Sox over 6.2 innings on July 1st, and after that has given up 19 earned runs in 19.1 innings, failing to pitch more than five innings in any of his last four starts. What the heck has happened to the Yankees’ brightest star?

Severino, for all his development in throwing sliders and changeups, still relies on his four seam fastball to attack hitters. It’s clearly his favorite pitch, and for most of the season it’s also been his most effective, as his pre-July 1st heatmaps will show:

This is Sevy’s usage of the fastball. He generally uses it to pound inside on right-handed hitters, and for most of the season he’s done that really well. It’s been difficult to hit him with any authority, and you can see the SLG%/P against fastballs here:

For the first three months of the season, batters just haven’t managed to hit Severino’s fastball for any power. Since Canada Day, the usage looks the same, but the results sure don’t:

Again, Sevy’s pretty steady at pounding righties. Only now, they’re pounding back:

So why is the fastball so hittable all of a sudden? It’s not a change in velocity:

Outside of his very last start on Saturday, Severino’s fastball has pretty well held constant all season. That’s really good news, since it’s a strong indicator that he’s healthy. A sharp drop in velocity is usually the first sign of injury.

The next question is, is this a mechanical change? Most power comes from a pitcher’s drive leg, so if there was something wrong with Severino’s footwork in his delivery, that’d be reflected in the velocity chart. Maybe there’s something in his arm slot, though. Take two nearly identical pitches, both 97 mph fastballs, one month apart:

Severino’s got a pretty standard three-quarter delivery, and it’s usually a very easy, repeatable motion. Now contrast that against an identical pitch from Saturday against the Royals:

There’s a slight dip in his release point, it’s just a little bit lower and the pitch is correspondingly flatter. It’s just one pitch, though. Can Sevy’s release point be less consistent now that it was earlier in the year?

It is! Not only do we see more deviation in his four-seam release point, but all three pitches are less consistent at the moment of delivery. Look at that first plot, notice how the slider and changeup overlap with the fastball much more consistently? That’s torture on an opposing batter, since he has no clue what the pitch is going to be, and when a guy is throwing 99+ on the inner third, you need as many clues as you can get.

Since July 1st, those overlaps have gone away. It’s now much easier for a batter to identify the hard stuff, and so even if Severino’s not “tipping” his pitches in the traditional sense, he’s allowing the hitter more clues into what he’s trying to do. With major league hitters, sometimes a couple inches of release point difference is all they need to start squaring up.

The differences in release point only ARE a couple of inches. There’s nothing particularly wild or concerning in Severino’s delivery. This may be a case of random fluctuation and regression to the mean all at once. As the ace of the staff going forward, though, it behooves Luis to focus on closing up those release point gaps, and return to the more consistent delivery we saw earlier in 2018.