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Justin Masterson’s (Almost) All-Fastball Dominance

Lou Marson had a pretty easy eight innings catching Justin Masterson Tuesday night against the Minnesota Twins. Any catcher would gladly receive for a performance like Masterson’s — eight scoreless innings, bolstered by six strikeouts and only blemished by four hits and one walk. And it just may have been the single easiest game a catcher has ever called. 104 times Marson put a sign down with his right hand. 103 times it was the ol’ number one.

Yes, merely a day after Sam Miller wrote this piece wondering if a pitcher would ever throw an all-fastball start, Justin Masterson was one fourth-inning slider away from doing just that. All but one of Masterson’s pitches sat between 89.9 and 97.7 MPH, and as the results of his start suggest, they were mightily effective, carving up Twins batters to the tune of 10 swinging strikes on top of the shutout performance.

Overall, 10 swinging strikes in just over 100 pitches isn’t an overly impressive mark. It’s good — at 9.7%, it’s well over his season average of 7.7% and above the league average of 8.5% — but even if Masterson maintained that rate for the whole season, he still wouldn’t land in the top 25 qualified starting pitchers.

This is because the fastball is the least likely pitch to induce a swing and miss. It makes sense — whereas the curveball and changeup are often about deception and movement, the fastball is a “here it is, hit it” kind of pitch. The fastball is a pitch at its best when hitting a corner where it’s not even worth it to swing, and if contact is made, it’s weak. This notion is supported by the data — according to TexasLeaguers.com, the league-average whiff rate on fastballs is only 6.0%, well below the overall whiff rate of 8.5%.

Masterson has had an immensely successful season with Cleveland this year, posting a 2.64 ERA and a 2.89 FIP. The reason for his success, both in Tuesday’s start and the season-to-date, is clearly his fastball. He goes to the pitch 82% of the time, the highest of any starter in the league, and although it usually isn’t quite as dominant as it looked against Minnesota, a whiff rate of 7.0% (according to the aforementioned TexasLeaguers) with the fastball is impressive, especially when hitters know it’s coming.

Hitters make adjustments, and one would imagine we’ll see a few more sliders from Masterson in his starts down the line, if only by necessity. But his fastball is a very special pitch, capable of inducing the swings-and-misses and ground balls that aces are made of. Tuesday was the best exhibition of just how powerful that pitch is for Masterson, and maybe someday soon we’ll see him eschew that one slider and truly treat us to the all-fastball start. If anybody is capable, it’s him.