Can Aaron Sanchez continue his ascent?

Aaron Sanchez had a breakout year in 2016. He established himself not only as the ace of the Blue Jays rotation, but also as one of the most exciting young arms in all of baseball. Throughout the year he forced management’s hand, first to slot him in as a starter out of spring training as a starter and then to allow him to continue in that role down the stretch. His persistence rewarded the Blue Jays with some stellar performances that helped the team clinch a wild card spot. Sanchez led the American League in ERA, posted a solid 3.9 fWAR, and had a career high in innings pitched in his first full year as a starter in the majors.

This was a marked improvement from his starts in 2015:

During the offseason, Sanchez added 20 pounds to his lanky frame, and it seemed to help him stay healthy and be more consistent with his delivery. He cut down his walks and improved his strikeouts, resulting in a much healthier FIP. The walks especially had been a problem for him through out his minor league career, and in his handful of starts in 2015 he continued to struggle with his command, so improvement to that number was a big indication of Sanchez’s development as a starter.

Having said that, there are still areas where Sanchez needs to improve to be consistent at the top level. He needs to make at least a couple of adjustments. First, he needs to improve his numbers against LHH, and second, he needs to develop his pitch mix.

Let’s look at his lefty/right splits for 2016 first:

It’s clear that Sanchez’s stuff dominates righties. He relies heavily on his sinker to generate an outstanding 61 percent ground ball rate, which allows him to keep the ball in the park. He also keeps his walks to a minimum.

However, against lefties Sanchez seems to change his approach, looking less like a contact-oriented ground baller and more like a slightly wild power pitcher. He only generates a 47 percent ground ball rate against lefties, and strikes out more batters, but walks a ton. Anecdotally it seems that he relies less on his sinker and tries to challenge opposite side batters, losing command in the process.

Let’s look at his pitch selection against both sides in 2016:

It seems that against LHH Sanchez trusts his secondary pitches less, and challenges batters with his four seamer more often while decreasing the use of his sinker dramatically. This may also help us understand his lack of command against lefties. Another interesting piece of information here is that Sanchez throws 12% of his changeup against LHH, and this is something he needs to further develop asit’s considered an effective pitch against opposite side hitters.

Another aspect of the game where Sanchez needs to get better is when he’s facing batters on the third time through the order. Let’s look at his numbers for each time through (ignoring his numbers on the fourth time through the order, as he only threw 4 ¹⁄₃ innings):

Although most pitchers generally see their performance drop from 1st to 3rd time through the order, it seems to be a bigger-than-usual issue for Sanchez. There’s a large increase in fly ball (FB%) against Sanchez on the third time through the order, though the drop in GB% is negligible. That’s probably an indication that hitters are able to square up his pitches better (as also indicated by the higher BABIP and SLG). This is probably another sign that Sanchez needs to develop his changeup for more effective use.

If we drill down deeper, and look at the slugging allowed on each pitch split by times through the order, we see that righties got much more comfortable with the sinker (slugging from .314 to .417) and the curveball (slugging from .263 to .556) the more they saw it. If Sanchez is going to stay effective deep into games, he’s going to need to throw his changeup more. It may be that he feels it’s not developed enough, or he might not have confidence and experience throwing it. He had shelved his changeup while pitching in relief in 2014 and 2015, and that might have something to do with its slowed development.

However, it’s not just against lefties that he needs to improve. He needs to vary his pitch selection against righties, and maybe use his changeup more often against them as well. His sinker is his bread and butter pitch, and will continue to remain so. It’s an explosive pitch, but overusing it may lead to less effectiveness. Developing his changeup may also help him with his control against lefties, against whom he relies quite a bit on his two seamer.

Aaron Sanchez has all the tools one needs to be a top-five starter in baseball. His has velocity, an explosive fastball, and a devastating curve ball, and he took a real step forward in 2016. 2017 should be an exciting year for all Blue Jays and Aaron Sanchez fans to see if he continues his ascent, and what kind of adjustments he makes going forward.