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Carlos Carrasco's incredible, vexing slider

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The Cleveland right-hander's performance has fallen off after last year's breakout, chiefly because the pitch that brought him greatness has betrayed him.

Carrasco has allowed more hits and more home runs in 2015.
Carrasco has allowed more hits and more home runs in 2015.
Ken Blaze-USA TODAY Sports

Most major-league starters throw a variety of pitches, each of which can help him to retire a hitter in some fashion. Fastballs, breaking balls, off-speed stuff — they all serve their purpose, or at least they should. For the pitchers who seek to take their game to another level, improving a single one of their offerings can give them the results they seek. However, if that pitch should decline, the hurler's play may come down with it.

Carlos Carrasco, at different times the jewel of the Philadelphia farm system and the main piece of that team's Cliff Lee package, struggled for several years to fulfill his potential. From his debut in 2009 to his forgettable 2013, he compiled 238.1 innings of 5.29 ERA, 4.08 xFIP ball. The latter mark suggested that he should have allowed fewer runs, but an elevated BABIP and HR/FB% (.325 and 12.9 percent, respectively) prevented that from happening.

Come 2014, Carrasco took a huge leap. He shaved more than a run off his xFIP, lowering it to 2.66; arguably more importantly, though, he brought his BABIP down to .274, and his HR/FB% down to 7.1 percent. Those improvements cut his ERA in half, to an indomitable 2.55. This new version of Carrasco ranked among the best pitchers in the world, and one pitch in particular brought him that success: the slider.

While pitching in the minor leagues with the Phillies, Carrasco didn't use the slider all that much, or at least to the extent that he's used it recently. Instead, he relied on his other three above average pitches — a fastball, a changeup, and a curveball. The latter two in particular stood out; Kevin Goldstein described them as "outstanding" and "nice", respectively. If Carrasco would make the leap, he'd do so on the strength of those two pitches.

And indeed, through his first several chances at a big-league career, Carrasco stuck by the changeup-curveball combination. Prior to 2014, he implemented the cambio 19.8 percent of the time, and the bender 12.3 percent of the time; those overshadowed the 8.8 percent rate at which he employed his slider. But that recipe didn't make much sense, because his slider topped the other pitches in his arsenal in most regards.

Carrasco's slider induced a whiff in 25.9 percent of its appearances (compared to 18.2 percent for the changeup and 11.1 percent for the curveball), a strike in 70.4 percent of its appearances (compared to 69.6 percent for the changeup and 62.5 percent for the curveball), and a hit in 29.8% of its times put in play (compared to 33.1% for the changeup and 32.8% for the curveball). Perhaps its tendency to leave the ballpark — it resulted in a home run 1.5 percent of the time, dwarfing the 0.7 percent mark of the other secondary pitches — scared him off. Whatever the justification, Carrasco didn't take advantage of what he had, and his output reflected that.

In 2014, two things changed. Carrasco moved to the bullpen at the beginning of the season; after coming back to the rotation, he saw increased velocity on everything he threw:

Pitch Type Velo (2009-2013) Velo (2014)
Fourseam 94.0 96.3
Sinker 92.7 95.5
Change 86.8 89.4
Slider 84.7 87.0
Curve 80.3 81.7

More power behind his pitches certainly helped Carrasco to post the aforementioned elite ERA and xFIP. The other change he made, though, had to do with usage. The changeup (13.1 percent) and curveball (9.1 percent) occupied significantly smaller sections of his arsenal. What displaced them? This monster:


Carrasco finally made the slider his primary breaking ball, upping its rate to 22.8 percent. With the higher velocity, that gave it more whiffs (29.2 percent), more strikes (78.7 percent), a lower BABIP (.213), and no home runs. Overall, it contributed 19.4 runs to Carrasco's campaign, the most of any such pitch in the American League. The dominance of that one pitch transformed Carrasco from scrub to star.

But 2014 has come and gone. For 2015, Carrasco has kept up the xFIP pace he set for himself last year, putting up a nearly analogous 2.73 mark in that area. His ERA, on the other hand, has jumped significantly, to a mediocre 3.94. And it all comes down to the pitch that once served him so well — the slider. Thus far, its whiff rate has slumped to 24.8 percent, and its strike rate has dropped to 71.2 percent; more relevantly, though, it's had a .345 BABIP and 1.0 percent HR%. Worth only 1.3 runs above an average slider, it's tumbled from its perch atop the majors, and has played the largest role in turning Carrasco back into an underperformer.

What could have set in motion such a precipitous decline? The usual culprit, velocity, doesn't deserve the blame — Carrasco's thrown the slider harder this year than last. Not content with a mere 87-MPH average on the pitch, he's upped that mark to 89.0, leading the AL. The cause must lie elsewhere.

Before breaking out, Carrasco consistently threw his slider low, as do most pitchers:


When making his improvement, he took that to the extreme, all but abandoning the high slider:


And based on his zone plot from 2015, two possible causes become clear:


There's obviously the drift back upward, a regression to the harmful tendencies of old. Beyond that, something odd presents itself: For whatever reason, Carrasco's grooved 9.0 percent of his 2015 sliders — much higher than any other pitch in his repertoire. On those hung pitches, hitters have gone 3-for-7 with a homer thus far, so they've certainly capitalized on Carrasco's temerity.

Still, this can't account for all the change. Something else has had a hand in the slider's fall from grace. The velocity may have improved, but the close relative thereof has not. To put it more clearly: Carrasco's slider doesn't move like it used to.

The classic Carrasco slider, traveling in the mid-80s on average, carried a 1.4-inch drop and a 0.3-inch slide. The 2014 iteration of the pitch, which gained a notable amount of bite, didn't shift too much in these regards — it moved 0.9 inches vertically and 1.1 inches horizontally. But the 2015 version has, somehow, abandoned the paths blazed by its predecessors. With 2.9 inches of vertical movement and -1.4 inches of horizontal movement, this slider is pretty new; its results presumably make Carrasco yearn for the slider of old.

Nothing obvious (to my knowledge, at least) has forced Carrasco to change the slider. He's thrown it just as often as last year, including situationally, and he hasn't dealt with any notable injuries thus far. Somehow, the pitch has just evolved, killing Carrasco's overperformance in the process. It still fares better for him (by most measures) than do either the changeup or the curveball, but it can't go toe-to-toe with the previous ones.

Although Carrasco always had top-of-the-rotation stuff — he didn't headline the Lee trade for nothing — he required some pitch adjustments before putting up top-of-the-rotation numbers. More adjustments have followed those, and the more recent ones haven't had the positive effects that the first ones did. Carrasco, as much as anyone, can testify to the fact that one pitch can make a huge difference.

. . .

All data as of Tuesday, July 21st, 2015.

Ryan Romano is an editor for Beyond the Box Score. He also writes about the Orioles on Camden Depot (and on Camden Chat that one time), and about the Brewers on BP Milwaukee. Follow him on Twitter at @triple_r_ if you enjoy angry tweets about Maryland sports.