Jun 13

Dallas Keuchel’s Slider Is Key

I doubt if anyone outside of Houston thought that the Astros would be 31-37 this late into the season, and while they’re still last in the AL West, the Astros have improved seven games upon 2013’s results through the first 68 (24-44) and currently sit a measly two games behind the injury-ravaged Texas Rangers.  This season, the Astros’ headlines have been dominated by George Springer and Jon Singleton (thank you Bud Norris), but maybe we should be paying more attention to Dallas Keuchel.

Entering 2014, the Astros’ lefty had posted a rather underwhelming 9-18 record across two seasons with an ERA of 5.20 in 239 IP while allowing a less than stellar H/9 of 10.4 and a WHIP of 1.54.  While there were signs that he was better than the traditional numbers might indicate, in particular his FIP of 4.25 last season, neither his ERA+ of 79 nor his H/9 of 10.8 in ‘13 screamed breakout candidate.  He’s young (Keuchel entered ‘14 just turning 26), so maybe those first two seasons were just a kid’s OJT.

What jumps out immediately when first looking at Keuchel’s stats so far is that his numbers have improved dramatically in nearly every category.  His WHIP has improved by nearly 55% over ‘13 (0.993 from 1.536), owing largely to dramatic drops in H/9 (7.1 from 10.8) and BB/9 (1.8 from 3).  His drop in ERA only seems steep unless you consider that his strong FIP of 2.81 indicates that Keuchel is pitching significantly better and not just getting lucky.  I suppose, then, the question is how?  What exactly is Keuchel doing differently this year as opposed to earlier?

I went out to both texasleaguers.com and brooksbaseball.net to examine the PITCHf/x data for Keuchel over the last three seasons.  First, it should be understood that pitch type in the PITCHf/x data is determined by an algorithm that has been modified and tweaked over the years, so while pitch type accuracy has improved those same classifications weren’t retroactively updated to prior seasons.  Second, this is my first attempt at deciphering this information, so my interpretations are probably wrong.  Third, I’m going to include a lot of pretty pictures and graphs to hide how wrong I am.

The Slider

I’ll first provide a few tables, then get to my interpretations.

Type Count Selection Strike Swing Whiff Foul In Play
FT 487 35.2% 57.7% 38.4% 2.7% 14.4% 21.4%
FF 280 20.2% 63.6% 41.1% 3.9% 15.4% 21.8%
CH 230 16.6% 57.8% 49.6% 13.0% 11.7% 24.8%
CU 202 14.6% 57.4% 36.6% 6.4% 10.9% 19.3%
FC 178 12.9% 63.5% 48.9% 7.3% 21.3% 20.2%
SL 3 0.2% 66.7% 66.7% 0.0% 33.3% 33.3%
FA 3 0.2% 33. 3% 33.3% 0.0% 0.0% 33.3%

2012 Pitch Results


Type Count Selection Strike Swing Whiff Foul In Play
FT 778 31.2% 61.1% 40.7% 4.2% 13.4% 23.1%
FF 619 24.8% 67.2% 42.3% 4.5% 16.3% 21.5%
SL 456 18.3% 67.5% 52.9% 20.8% 17.8% 14.3%
CH 322 12.9% 64.6% 50.9% 14.9% 13.0% 23.0%
CU 179 7.2% 52.5% 31.8% 8.9% 7.8% 15.1%
FC 139 5.6% 60.4% 38.1% 7.9% 14.4% 15.8%

2013 Pitch Results


Type Count Selection Strike Swing Whiff Foul In Play
FT 531 40.2% 70.6% 46.3% 5.6% 17.1% 23.5%
SL 318 24.1% 56.0% 49.1% 24.2% 14.2% 10.7%
CH 209 15.8% 60.8% 50.2% 16.3% 12.0% 22.0%
FF 189 14.3% 66.1% 38.1% 2.1% 14.3% 21.7%
FC 72 5.5% 58.3% 30.6% 1.4% 16.7% 12.5%
CU 1 0.1% 100.0% 100.0% 100.0% 0.0% 0.0%

2014 Pitch Results

Essentially what you’re looking at is the various pitches PITCHf/x has tracked for Keuchel over the last three seasons, broken out by type.  For the most part, you don’t need to worry too much if he threw a 2-seamer (FT) or a 4-seamer (FF) for my discussion since I’m more interested in Keuchel’s increased use of his slider (SL) and the near abandonment of his cutter (FC).  In 2012, Keuchel barely registered the use of a slider (honestly I question the classification between slider and cutter since both registered at nearly the same average velocity) and by 2014 he throws the pitch nearly a quarter of the time.

Also, look at how Keuchel has moved away from using his cutter, a pitch that wasn’t particularly effective for him.  In ‘12, batters saw the pitch 12.9% of the time, missing at just 7.3% of the swings they took.  Keuchel allowed a .262 average off of the cutter, with five extra-base hits (two home runs) in just 43 plate appearances.  In ’13 the cutter was hit even worse, being smacked around the yard to a .333 average with five extra-base hits (three home runs) in only 29 plate appearances.  This season he’s been more fortunate with the hits against it, allowing a .200 average, but he’s thrown it only 5.5% of the time.

2013 saw Keuchel begin to use his slider more often, throwing the pitch 18.3% of the time, and look at the results:  the pitch was either fouled off or missed completely 38.6% of the time he threw it.  Batters hit .248/.262/.402 against it, striking out 52 times in the 122 plate appearances for an impressive K% of 42.6.  That was overwhelming his most effective out pitch in 2013, and Keuchel has carried his increased trust in the pitch over into the current season.  This season, batters have hit .150/.171/.213 against his slider, and they’ve struck out in 56.1% of the plate appearances when he’s thrown it.

Diving deeper into the numbers, here is a breakdown of the pitch’s effectiveness from season to season:

Year Velocity Vertical Horizontal Spin Angle Spin Rate
2012 84.1 4.73 0.68 174 916
2013 80 0.15 -2.82 243 768
2014 79.6 -1.7 -3.92 271 903

Slider Pitch Results

Perhaps a graphic would help explain better:


Spin Movement

From the numbers, it’s clear to see that in ’14 the pitch is breaking away from lefties (digging into righties) significantly more with a definite horizontal drop.  In effect, the pitch is starting to become nasty.

A side effect of the increased movement, and also likely a good reason why batters are hitting only .150 against his slider is the end result of the pitch missing the strike zone more frequently.  In ‘13, Keuchel threw his slider 459 times with an end result of 310 strikes and 149 balls.  67.5% of the time his slider was in the strike zone when it crossed the plate or met wood.  In ‘14, the pitch has been thrown 318 times for 178 strikes and 140 balls.  The slider ends with a result considered a strike only 56% of the time.  Keuchel has become effectively wild, delivering a pitch too appetizing to lay off but too difficult to square up.

We’re talking end results here, though, and while he’s allowed fewer hits to left handed batters this season he’s remained nearly identical in striking lefties out (30%), but right handed batters this season he’s buried.  In ‘13 they hit .304/.363/.469, striking out around 16.6% of the time while in ‘14 those numbers have dropped to .219/.262/.329 while striking righties out 19.8% of the time.  There are advantages, then, for being able to better neutralize righties when Keuchel sees them 72% of the time so far.

Ground Balls

Another thing I noticed about Keuchel is that he’s inducing a groundout in nearly a third (31.3%) of hitters’ at-bats this season.  The biggest reason for that increase (in ‘13 hitters grounded out 23% and in ‘12 it was 24.3%) is a huge spike in groundouts via his 2-seam fastball.  In both ‘12 and ’13 Keuchel forced ground balls on around 64% of at-bats while in ‘14 that number has spiked to 78.9%.  Hitters are putting the ball in play at roughly the same rate (23.5% in ’14 and 23.1 in ‘13), though they tend to foul it off (17.1%) and whiff (5.6%) more in ’14 than in previous seasons.  Last season Keuchel relied upon the two-seam and four-seam fastballs, which were nearly identical in velocity though differing in movement.  With an increase in the use of the slider, and the 10 mph difference in average velocity, batters seem to be more off balance and able to wait on a pitch to drive.

Release Point

I’m not even going to pretend to speak intelligently upon this point.  I just found this interesting.  Here are the release points from the last three seasons.


2014 Release Points


2013 Release Points


2012 Release Points

I found it interesting that in the current season, Keuchel’s release point for his pitches seem to be more tightly grouped than in previous years.  At a very basic level, I would surmise that this would cause batters more difficulty picking up the pitches seeing as they are delivered from a more consistent release point, but I refuse to make that assumption on what I know now.  Just interesting is all.


I like pleasant surprises, and the emergence of Keuchel this season definitely qualifies.  Maybe by the end of the season we’ll call this one of those small sample size blips, but I’d like to believe it’s about a young pitcher growing more comfortable with his secondary pitches.  This bodes well for the Astros.  Already, Keuchel has accumulated 2.3 fWAR on the season, a huge jump from his high of 1.0 last season (-0.7 in ’12), and perhaps he won’t top the leaderboard all season, but I’m curious to see if he at least keeps in touch.

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