What Makes Marcus Stroman Effective?

Toronto Blue Jays starter Marcus Stroman has shown flashes of brilliance during his brief career, but has yet to put it all together for a full season. He missed most of the 2015 season with an anterior cruciate injury, returning in September when he pitched four superb regular season games (1.67 ERA in 27 innings, although his post-season start was less impressive). In 2016, though, he was barely average, putting up a 4.37 ERA (98 ERA+) en route to a 9-10 win-loss record over 32 starts. However, his 3.71 FIP and 1.289 WHIP suggested that he had some bad luck. He showed only a slight platoon split, with left-handed batters putting up a .748 OPS against him and right-handers OPSing .698.

In his two starts so far in 2017, following an impressive appearance (one hit over six innings) to win the World Baseball Championship title, Stroman has looked very strong, posting a 1.76 ERA and a WHIP of 1.043, including a complete-game loss to Milwaukee in which he only gave up two runs.

What he throws. Stroman has a large and complex arsenal of pitch types, most of which blend imperceptibly into each other. His most common pitches are a two-seam fastball (“FT”) that averages 92.9 mph, a cutter (“FC”), and a curve (“CU”). He also throws a slider (“SL”) that blends into the cutter at the top and the curve at the bottom, a changeup (“CH”), and a four-seam fastball (“FF”). The latter is quite distinct from his two-seam, not only being about one mph faster (93.7 mph), but also having much more vertical “rise” than his two-seam version:

Pitch usage and trends.
Stroman throws his two-seam fastball about half the time (52.7% of pitches overall), and uses it roughly similarly to right- and left-handed batters. When ahead in the count, Stroman is much more likely to go to his cutter (35.5% of pitches, compared to his overall cutter usage of 22.8%) and less likely to use his two-seamer (30.1%). The reverse is true when he falls behind, when he uses his two-seam fastball 70.7% of the time and uses just 14.2% cutters. His changeup, slider, and four-seam fastball are infrequent in any situation, but are a little more common when ahead in the count:

Although the sample size in 2017 is too small to have any confidence in trends, so far Stroman has used more two-seam fastballs than during last season (70.2% of pitches), with his cutter making up most of the remainder (18.6%):

Over the course of the 2016 season, Stroman changed his pitch usage significantly. About halfway through the season, he cut back on his curve and slider and increased the use of his cutter, until the last three games of the regular season when he threw his curve again. Also starting about halfway through the season, he started to mix in occasional four-seam fastballs, and apparently become more comfortable with them toward the end of the season. His changeup followed the opposite pattern, being mostly phased out as the season progressed:

 Pitch value. All three of Stroman’s most common pitches (two-seam fastball, cutter, and curve) were around MLB-average in value in 2016, based on total bases yielded per 100 pitches and on balls per 100 pitches. His curve is the only one of those three to have significant platoon splits, being much more effective against left-handed batter than righties. The other three pitch types are all used much more sparsely, but with the exception of the changeup are also around league average in quality. His changeup was very poor to left-handed batters (25.3 total bases per 100 pitches; it is cut off in the chart here), but since he only threw 91 changeups to lefties in 2016, the damage was limited. Rare though his four-seam fastball was, it was quite effective, especially to right-handed batters:

Stroman is renowned as a ground-ball pitcher, ranking first among pitchers with at least 2,000 pitches in 2016 with 59.8% ground balls. (Including pitchers with at least 1,000 pitches, and therefore allowing relievers, drops Stroman well down; Zach Britton becomes the leader with a 78% groundball percentage.) Stroman gets ground balls from his two-seam fastball (64% GB%), but also from his slider and cutter (62.5% and 58.0% GB%, respectively).

Pitch location. Each of Stroman’s three most frequent pitches target the bottom of the strike zone, or just below it. His two-seam fastball is the most likely to be in the strike zone, and to right-handed batters the pitch had two typical locations – inside, or at the bottom outside edge:

Two of his three less common pitches (four-seam fastball, changeup, and slider) also typically ended up at the bottom of the strike zone, with his four-seam fastball being the only pitch Stroman throws that tends to target the top of the strike zone:

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Featured image courtesy of Todd Korol/Toronto Star.