Can Aroldis Chapman succeed when he’s older without a blazing fastball?

With Aroldis Chapman back in pinstripes, there is very little doubt that the Yankees will have their shutdown closer in 2017. A few of our writers have already done a great job discussing the social implications of the Chapman signing, but from a baseball perspective, Chapman figures to be a dominant closer for at least a couple of years. Even in a suspension-shortened season, Chapman was his usual superb self in 2016 with a 1.55 ERA in 58 innings.

In the World Series, Cubs manager Joe Maddon did not hold back in his usage of Chapman, making the controversial decision to bring him on for an eight-out save in Game 5. In Game 7, Chapman’s velocity was down, and the effects were palpable. He threw 35 pitches and got four outs, also giving up two runs. This begs the question: what will happen to Chapman’s effectiveness if he loses velocity during the course of his five-year deal with the Yankees?

Predictably, as a guy who has thrown a baseball at 105 mph, Chapman is a freak athlete. According to George King at the New York Post, Chapman used to beat Reds’ speedster Billy Hamilton in footraces. This clip from ESPN’s Sports Science also gives a good idea as to just how athletic he is:

Age will undoubtedly make it difficult for Chapman to maintain the same level of flexibility and arm speed, and his violent mechanics do not always give him the best control or command. Hitters around the league are adjusting to pitchers who regularly sit in the high 90s, so Chapman with diminished velocity might be an issue for the Yankees.

In all likelihood, the Yankees are probably betting on Chapman’s ability to continue to evolve, in addition to his ability to retain his velocity. This season, he set a career low in walk rate, while throwing more pitches in the strike zone than ever before. For most of his career, walks have been his only weakness, as he has been good about keeping the ball in the yard, while pitching in hitter-friendly ballparks.

On rare occasions, Chapman will mix a changeup into his usual fastball/slider combo. According to Pitch F/X, he set a career-high Zone% for both his fastball and slider in 2016. But the most drastic increase came through his slider, which he threw in the strike zone 54.1% of the time. In 2015, only 41.8% of his sliders found the strike zone. Topping out at 93 mph, Chapman’s slider has wipeout potential, and he may be starting to show greater confidence with it.

In Andrew Miller, the Yankees signed a dominant lefty with a history of giving up free passes. One of the many things that made Miller so great was that he actually improved throughout the life of his contract. If Chapman’s improved control and/or command is here to stay, it could potentially make up for diminishing velocity.

Either way, fans can expect more heat in the short term. As of 2016, he appears to be as much of a flamethrower as ever, topping out at 105 mph. Hopefully, his elite velo is here to stay. If not though, the Yankees think he will still be alright.

Data is courtesy of FanGraphs.