What Luis Severino needs to improve on for his next start with the Yankees

Tomorrow marks the second big league start of Luis Severino's career and everyone–him, the Yankees, the fans–hope to see him improve from what he showed against the Red Sox. Last time out, the 21-year-old allowed only one earned run on two hits and no walks while striking out seven batters in five innings, giving the Yankees an outing they have been craving for months. Unfortunately, while his final line looked good, he could have done much better in terms of pitch efficiency in order to go deeper into games.

Throughout the course of the game, Severino threw 94 pitches in five innings, which isn't exactly how you go deep into games or give the bullpen a break. In his five innings, he threw 17 pitches in the first, 25 in the second, 12 in the third, 25 in the fourth, and 15 in the fifth, but amazingly never walked a batter. His issue in his first appearance was his inability to put hitters away on two strikes after allowing 11 foul balls on two-strike counts, and his struggles to throw strikes on a consistent basis, leading to seven full counts overall. It worked out this time against a terrible Red Sox lineup, but a more competent offensive threat could take advantage if he doesn't improve some things on the mound.

Release Point

The first thing he needs to work on is developing a consistent release point because it's very clear that his arm angle is higher and closer to his body when throwing a fastball as compared to his breaking pitches:

It isn't something that's incredibly noticeable to the naked eye right now, but he runs the risk of tipping his pitches if things separate any further. Pitchers have a tendency to drop their shoulders, and therefore arm angles, when trying to snap off breaking pitches and get a better angle to get some extra torque on their pitches. It might not be something he can improve on right now, and it might not be something that will ever become an issue, but it's at least something to keep track of going forward. If he's getting hit hard a month from now, this could be something to check back on.

Fastball for Strikes

Severino's fastball is thought to be his best pitch, and while it possesses a lot of movement as we saw in his first start, he needs to do a better job of keeping that movement in the strike zone. Obviously, having a straight fastball is not something you want, as we saw with Phil Hughes, but on the other end of the spectrum, too much movement without pinpoint accuracy can be detrimental too.

His fastball was the pitch he threw outside the zone most often and while he elicited some swing-and-misses, it isn't really a strategy to stick to. The best pitchers try to keep their fastballs out of the heart of the strike zone, of course, but he dispensed some fastballs that weren't even close and he needs to work on that. As Eno Sarris of Fangraphs showed, some of his wildness could come down to the adrenaline rush that is associated with a major league debut and overthrowing pitches, so it's definitely not clear yet how he will pitch going forward.

Slider Command

One of Severino's best pitches has been his slider, but he proved to be very hit-or-miss with it during his August 5 start. A slider is obviously a pitch you want to bury out of the zone in order to get the batter to chase, but he didn't have that part of his game going for him:

He threw a total of 10 sliders out of the zone and seven of them didn't even lure a swing. He needs to figure out a way to convince batters to chase his slider offering out of the zone, otherwise the pitch just becomes an automatic ball. Again, this could be a matter of nerves firing off a shoddy slider, but he needs to show that he can make his slider at least look like a strike in order to fool hitters.

When Luis Severino takes the mound again against the Cleveland Indians, he needs to maintain the same confident composure on the mound that he showed last time out, but he also has to be able to trick hitters into thinking he's going to throw a strike. He uncorked many offerings that didn't look very hittable, so batters weren't chasing. His pitches have enough movement to miss bats, but he actually has to keep his pitches near the strike zone in order to trick them. Hopefully he shows some improvement in tomorrow's game in order to get further into games and become even more of a force than he showed he can be in his first game. Maybe it's just a matter of getting his nerves under control and remaining consistent.