Mike Bolsinger Thrives in L.A. with Effective Two-Pitch Mix

Mike Bolsinger Dodgers

While the mid to back-end of the Dodgers’ rotation has been largely an impromptu affair up to this point with Hyun Jin Ryu and Brandon McCarthy on the disabled list, Don Mattingly and the rest of Los Angeles’ front office have been pleasantly surprised by the production of one Mike Bolsinger, who seems to have hit his stride as a fill-in starter thus far in 2015. On Saturday, the 27-year-old right-hander allowed one hit and goose eggs in the runs and walks allowed departments, fanning eight San Diego Padres hitters and requiring just 92 pitches to complete his masterful eight-inning performance. It was Bolsinger’s second consecutive shutout start (and third straight winning decision) after blanking the Rockies across six frames last Sunday in Chavez Ravine, giving the former fifteenth-round pick a sterling ERA of 0.71 over his first four starts with Los Angeles’ rotation — lowest among starting pitchers with at least 25 innings this season, and by a considerable margin at that.

When we look at what Bolsinger has accomplished thus far in 2015, we ought to start paying more attention, because a few things stand out. The first is good fortune, as he’s stranded 96.9% of runners who’ve reached base against him while holding opposing lineups to a feeble .213 batting average on balls in play. Neither are likely sustainable, but they’ve nevertheless helped get him to this point. The second is quality of contact, or perhaps more tellingly, an obvious lack of it. Not only has Bolsinger’s ground-ball rate inflated to 61% this season (up from 50.3% last season with Arizona), but he’s ceded just eight hard-hit balls against 92 total batters faced to this point, which computes to a hard-hit average of .096 for opposing hitters, third-lowest among starters with 25 innings. The third is his strikeout-to-walk ratio, which has increased from 2.82 last season (below league average) to 3.67 this season (higher than 75% of the league). And the fourth — and this is especially important — has been his simplified yet highly effective arsenal, relative to the one he featured last season with Arizona:

To understand why Bolsinger has somewhat unexpectedly thrived with Los Angeles this season, we should first look at the changes he’s made to his arsenal, because quite clearly, he’s made some. We can tell that Bolsinger worked out of a three-pitch mix of fastball, cutter and curveball in 2014 with Arizona, back when he posted an underwhelming 5.50 ERA and 4.01 FIP over 52.1 innings dispersed throughout the regular season. None of those offerings were thrown any less than one fourth of the time and none were thrown at a 40% clip or higher, which tells us that Bolsinger, generally speaking, had confidence in each. You’ll often here scouts and talent evaluators say staring pitchers need at least three quality pitches to succeed long-term in the big leagues, and that’s true far more often than not. More pitches create more opportunities to keep hitter off balance. Bolsinger didn’t succeed by anyone’s measure last season, but his relatively balanced arsenal tells us he at least wanted to keep hitters honest.

Now look at this season. As you’ll see, Bolsinger’s repertoire has been pretty dramatically altered from a state of harmony between fastball-cutter-curveball last season to two offerings this year — and those offerings happen to be cutter and curveball, which now eat up a hefty 90% of his arsenal. That’s an odd combination, to put it bluntly. The most typical combinations for two-pitch starters (and predominantly inexperienced starters) is either fastball-curveball, fastball-slider, or perhaps even fastball-changeup. But cutter-curveball? Weird. It kind of makes sense, though. Opposing hitters slugged .552 against Bolsinger’s four-seamer last season, which means opposing hitters were Giancarlo Stanton (.555 SLG%) versus his fastball in 2014. So when you look at it that way, Bolsinger’s apprehension to throw the fastball this season can be readily understood.

pitch speed

The cutter-curveball combination has enabled Bolsinger to effectively mix his pitches and keep hitters off balance  in 2015 | Photo and data courtesy Brooks Baseball

But the cutter-curveball combo doesn’t equate to success on its own. Execution and the element of surprise (comparison shown above) have contributed to his early success with the two-pitch mix. As far as command and execution are concerned, Bolsinger has played effective keep-away with his cutter to right-handed hitters this season, throwing 59.2% to the outer-third of the strike zone (up from 43.4% last year), and against lefties, he’s busted them inside 47.7% of the time (up from 23.1% in 2014). The result has been significantly fewer well-struck balls. Opponents’ hard-hit rate against Bolsinger’s cutter has tumbled from 30.9% in 2014 to 9.7% this season, a product of the fact that they’re beating it into the dirt 70% of the time compared to just 47.2% last year. Establishing the corners with his cutter has helped Bolsinger’s curveball play up, too; opponents have whiffed on 36.2% of their swings against his curve, up from 24.2% in 2014.

The season is still young and Bolsinger’s starting role with the Dodgers’ rotation is even younger. But we’re beginning to get a sense for why this 27-year-old castaway Diamondbacks prospect has succeeded so far this season: A fairly dramatic change to his arsenal, command of his cut-fastball and the element of surprise that comes along with his curveball — all things that have enabled him to induce weaker contact, fewer balls in play falling for hits and an improved strikeout-to-walk ratio. Quite obviously, no one is suggesting Bolsinger will maintain his current pace of run prevention; suggesting as much would neglect the fact that he’s been decently fortunate thus far. But it will nevertheless be interesting to see how the cutter-curveball combination will work for Bolsinger as we trudge deeper into the regular season, because Mattingly and the Dodgers will need him at his best.

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Statistics courtesy of TruMedia Networks LLC unless otherwise noted or hyper-linked.

Alec Dopp is a contributor to Gammons Daily. Follow him on Twitter @AlecDopp.