Raising Aces: Debut Ante: Luis Severino

The Yankees largely stood pat while the other contenders were wheeling and dealing up to the trade deadline in order to bolster their rosters for the stretch drive, but they did have one ace up their sleeve (or down on their farm, as it were). Luis Severino entered the season ranked number two on the Yankees prospect sheet here at BP, on the heels of a mid-90's fastball and a minor-league track record of dominance. He ranked at number 51 on the Top 101 prospect list prior to the season, and in our Midseason list of Top 50 prospects Severino had shot up to the ranking of 28th-best prospect in the game. The Pinstripes called up the right-hander to make his major-league debut on August 5th against their arch rival Red Sox.

Game Stats

Severino had an exciting debut, with heat that squatted in the mid-90's and touched 98 mph on the gun to go along with a slider-cutter hybrid, a pitch that he threw in the upper 80's to low 90's with late break and left his hand on a fastball flight path. The slutter worked as his put-away pitch, finishing off five of his seven strikeouts on the day, with tight break that was just enough to sneak under Boston bats. Most impressive was his fastball command, as Severino was nailing targets while tossing in some subtle movement to give the pitch life.

The fastball command took a step backward in his second outing, and though the box score shows only one walk charged against him, Severino's control of his arsenal wavered throughout the ball game. There were times in the game where he clearly didn't trust the fastball and leaned on the slutter to bail himself out. He threw a total of 38 breaking balls of his On the bright side, his pitch efficiency was improved, facing 24 batters with only three more pitches thrown than he had used in 18 plate appearances the game prior. Of course, the efficiency was the result of opposing batters taking more swings and making more contact on hittable pitches.

Severino's changeup received a lot more attention in the off-season than did his slutter, and in support of the scouting reports Severino's change showed the makings of a plus pitch when it made an appearance. I was looking forward to seeing more of his off-speed stuff, as the development of that pitch gives him excellent long-term potential with the type of arsenal to stay in the starting rotation.

Mechanics Report Card

I gave Severino excellent scores on his mechanics report card in the 2015 Starting Pitcher Guide, with grades of 55 or better in every category. The power scores that anchored that report card—including 60-grade momentum and huge torque that triggered a 65 on the 20-to-80 scale for hip-shoulder separation—were largely intact, but the momentum was inconsistent, particularly in the second start of Severino's season. The torque stands out due to a massive twist with the upper half paired with some scapular loading, and though he doesn't have a generous delay to his trigger after foot strike, the hip-shoulder separation was impressive when he lined up the gears.

The volatile pace to the plate was the issue that was underpinning his problems with pitch command, but when he had the motion in a groove (as he did for much of the first game), then Severino had a solid initial burst that picked up acceleration through the stride phase of the delivery. At his best, the right-hander finished with kinetic energy flowing toward the target after release point and follow-through, though his line to the plate was inconsistent and often veered glove-side late in his motion. Things got worse from the stretch, where Severino slowed his pace to the plate and exaggerated a lean-back toward second base during his stride, and these elements could conspire to wreak havoc on his timing and sap his effectiveness with runners on base. His upside in the momentum category helps to solidify the 60-grade seen on his above report card.

The power scores were consistent with what I had seen from Severino last season, but the grades for stability were completely different. While still volatile and though upside skewed the scores upward, last season I saw enough of his balance and posture to give him scores of 55 in both categories. But what I saw from the his first two starts was far from average, and though I will grant some leeway given the commonality for young pitchers to sacrifice stability in the name of power in the debuts, the shaky foundation to his delivery was a common theme that raises some concern over his immediate prognosis. The instability had a ripple effect on his mechanical repetition, and though he earned the 60-grade that is so rare to see among minor-league arms, that consistency of timing was compromised in his first two turns at the highest level.

His balance still flashed above-average on his best pitches, but there was more drop to his delivery, along with a pervasive tendency for Severino to lean toward the first-base side during his motion. Sometimes that lean started early with a back-side drift as he reached maximum leg lift, while other times he stayed on line until foot strike. The tilt to the first-base side perpetuated into release point, with the combination of his early drift and a late posture-change as he tilted the spine for a higher arm slot. In contrast to his balance, I didn't see any pitches with above-average posture from Severino in his first couple of games, and I don't expect him to make the necessary improvements within this season, so his high ceiling—which is built on a shaky foundation—will need to stay intact for a couple more months.