What has changed for Luis Severino since last year?

Luis Severino’s 2016 season has been something of a nightmare. He has endured injury and demotions to the minors, while allowing runs at an unsightly rate of 7.54 per nine. After giving up seven runs to the lowly Rays, Severino was sent down to Triple-A yet again.

That Severino has struggled so much has been somewhat surprising. The 22-year-old excelled in his first brush with big league hitters last season, posting a 2.89 ERA and striking out 56 batters over 62.1 innings as a rookie. He has fallen well short of the expectations he generated with such a promising rookie performance. What has changed since 2015?

A few main problems stick out with regard to Severino’s troublesome sophomore season. First, he has had peculiar struggles with right-handed hitters. In 2015, Severino dominated righties, yielding only a .267 OBP while striking out nearly 28% of the right-handers he faced.

This year, righties are batting an unseemly .330/.380/.610 against Severino, and his strikeout rate has fallen below 20% versus right-handed hitters. This strange platoon split has followed him during his time in the minors, too, as minor league righties have run up a .279/.328/.459 line against Severino.

Why are right-handed hitters tattooing Severino? It might be a result of something that Jason noted yesterday; hitters in general just aren’t having as a hard a time making contact against Severino this year. From Brooks Baseball, here is a heat map illustrating the rate at which Severino has generated whiffs against righties, from 2015 and 2016:

Hitters just aren’t swinging and missing at fastballs up out of the zone and sliders in the dirt the way they were last year against Severino. This idea is borne out in his plate discipline numbers from FanGraphs, as his opposing hitters’ out-of-zone and in-zone contact rates have both risen this year.

Another big difference between Severino’s two seasons has been the damage opposing hitters have incurred on fly balls. Fly balls in general are more harmful than groundballs, but even so, the league as whole still only has a .173 OBP with a .544 slugging percentage on fly balls.

Those marks pale in comparison to the numbers hitters have put up on fly balls against Severino. After allowing a well above-average, but not quite disastrous, 1.070 OPS on fly balls in 2015, Severino has surrendered a simply untenable 1.447 OPS on fly balls in 2016. On fly balls, which on average turn into outs 82.7% of the time, hitters are running a slugging percentage above 1.100 against Severino.

Part of those inflated figures could be attributed to luck, but it appears that Severino’s fly ball numbers can also be explained by his hard contact allowed. According to FanGraphs, his hard contact rate has ticked up, from 26.3% to 29.9%. And, while raw exit velocity on its own still doesn’t tell us much, Severino has allowed a hit velocity of 95.8 mph on balls hit in the air. That ranks seventh-highest among pitchers with at least 100 batted balls, and places Severino among names like the dearly departed Ivan Nova, and fellow Triple-A pitcher Tim Lincecum.

So, Severino can’t get like-handed batters out, and every batted ball in the air he yields seems to be well struck. That is the kind of the thing that needs to happen to post a 7.12 ERA, as he has. Is there any good news? Well, that depends on how you look at it.

Looking at Severino’s basic underlying numbers, very little appears to have changed between 2015 and 2016. In 2015, he struck out 22.0% of the batters he faced, while walking 8.6%. Those figures aren’t much different this in 2016, as he has struck out 20.5% of batters and walked just 6.1%. His groundball rate is still above average at 48.3%, while it hung just above 50% last year. Plus, it’s not like Severino has lost his stuff at age-22, with his fastball velocity having increased this year to nearly 97 mph.

The most basic indicators of performance suggest that Severino hasn’t undergone a massive change from last year to this year, despite the huge difference in on-paper results. In truth, it’s just very difficult to see an ERA increase by over four runs without running into some bad luck.

Bad luck probably has hampered Severino, in the form of both a sky-high .350 BABIP and an oddly low 56.1 strand rate. Even though hitters have scalded balls in the air against Severino, its hard to imagine such a high BABIP sustaining itself. The league average strand rate is 72.9%, suggesting poor sequencing has led to some of Severino’s run prevention troubles.

In totality, Severino’s true level of performance in his young major league career probably falls somewhere between 2015 and 2016. Severino’s strikeout and walk rates in 2015 were very similar to what they were now, but he also ran a very high strand rate and low BABIP in 2015. It seems very possible that Severino, while certainly worse this year, simply wasn’t quite as good as he appeared last year, and hasn’t been as bad this year as his run totals would indicate.

So the good news is that despite how bad this season has gone for Severino, there is evidence that he hasn’t that much worse than last year. The bad news is that that same evidence suggests Severino wasn’t quite as great as he seemed to be in 2015. Regardless, with the Yankees short on starters and September roster expansion coming soon, Severino likely won’t spend too much time in the minors. If and when he returns, the Yankees must hope their young starter can generate results the way he did last season.