Tanaka's edge against Trout

Masahiro Tanaka had seven strikeouts en route to his first win at Fenway Park on Apr. 22. Michael Ivins/Boston Red Sox/Getty Images

The day after Masahiro Tanaka shut down Boston’s lineup, some of the Red Sox hitters noted that you just don’t see that many starting pitchers who throw as many splitters as Tanaka.

“Closers, yes,” said Jonny Gomes. “Relievers, yes. But not starters.”

Even when Tanaka pitched with a sturdy lead, the Red Sox hitters noted that Tanaka kept coming at them with the splitter, one after another.

Tanaka’s splitter is not only regarded as one of the best in baseball -- maybe the best, because of its extremely late movement in its journey to the plate -- but the fact that he throws so many separates him.

So far this season, Tanaka has thrown his splitter on about 22 percent of pitches, according to FanGraphs. To put that number in perspective, only two starters threw their splitters more than 20 percent of the time last year: Hisashi Iwakuma and Hiroki Kuroda, two older pitchers. Only nine starters threw a splitter more than 10 percent of the time.

So not only has Tanaka demonstrated that he’s pretty good, with the ability to pitch to the edges of the strike zone, he is also highly unusual in what he throws.

Tanaka will face Mike Trout in the first inning on "Sunday Night Baseball" (8 ET on ESPN and WatchESPN), and interestingly, the splitter is the pitch against which Trout has struggled the most in his big league career, according to FanGraphs. He has done a lot of damage so far this season against two-seam fastballs and four-seam fastballs, but not against the splitter (small sample size alert):

Runs above average for each 100 pitches, 2014 season

Fastballs (four-seamers and other unclassified): 2.31

Two-seam fastballs: 7.17

Cutters: minus-4.76

Splitters: minus-7.48

Runs above average for each 100 pitches, career

Fastballs (four-seamers and other unclassified): 1.82

Two-seamers: 2.04

Cutters: 1.94

Splitters: minus-1.61

Tanaka told reporters Saturday that he really doesn’t know that much about the Angels’ hitters. But how he pitches to Trout in his first plate appearance may give us the first indication of whether the Angels’ center fielder is going to get a steady feed of splitters from Tanaka until he shows he can turn them around with authority.