Joe Kelly: Perennially an Adjustment Away

Joe Kelly always seems just a tweak away from greatness. He owns one of the biggest fastballs in the game, and has decent secondary pitches that don’t deserve scorn either. His command isn’t great, but he’s no Henry Rodriguez either. Throw a little bit more of one pitch, or a little bit less of another, the thinking has gone, and we’ll finally see greatness from the guy to match his athleticism and velocity.

You might have to admit that the latest tweak, suggested publicly by his manager, makes you wonder if there’s a fatal flaw that will forever keep the 26-year-old Red Sox starter from realizing his potential. It’s already the third such tweak that either the player or the team has discussed since they acquired him late last year.

One of the first prescriptions came from Curt Schilling. On air, he’s talked about Kelly using the four-seamer more often, especially high. That would change the eye level and up the velocity on the pitch, two things that should help him strike batters out more. Makes sense, and it seems that, at least on some level, Kelly has listened.

Before the trade, his pitching mix from Brooks Baseball, with velocity, average fastball height as it crosses the plate, and whiff rates.

Pitch Type Freq Velo (mph) swSTR% Vertical Loc
Fourseam 10.3% 95.8 6.4% -0.2
Sinker 57.2% 95.4 5.1% -0.3

And then after the trade.

Pitch Type Freq Velo (mph) swSTR% Vertical Loc
Fourseam 15.5% 96.5 8.5% -0.1
Sinker 52.0% 96.0 3.6% -0.3

More four-seamers. Slightly higher in the zone. Getting more whiffs. It hasn’t been enough to change Kelly’s fortunes, and recently he swore off the approach. Check out the lede from the game story on a recent start:

SEATTLE, Wash. — Here’s what a successful day at the office looks like for Red Sox right-handed starter Joe Kelly: 14 ground ball outs, three fly ball outs and two strikeouts.

The key to inducing so many ground ball outs?

“I threw one four-seam fastball,” he said. “I just stayed with my two-seam all the time because I feel like I had command on both sides (of the plate). The other day I was throwing more four-seams and and just yanking them off the plate.”

Going into this season, Kelly was ecstatic about his slider. According to the pitcher, it was the first time he’d thrown the slider in years. Rob Bradford remembers it as the slider that led to so much success at UC Irvine. And after his first outing, it was easy to fall into the same excitement that led Kelly to declare he was going to win the Cy Young this year.

For sure, the slider has changed.

  Freq Velo swSTR Horiz Move Vert Move
Slider Before 9.6% 83.8 15.5% 4.8 -1.9
Slider ’15 14.1% 86.3 22.5% 3.3 -1.9

It’s harder and straighter now, and it’s getting more whiffs. Who knows what Kelly called his last slider, but this new slider is looking good. He should throw it more! It’s a top-ten slider among starters! He is, but not by a ton. And again, his swinging strikes are up a bit, but not a ton. He’s still tied for the fastest fastball in the big leagues, with two other guys that don’t get the whiffs you’d expect.

Now the most recent edict.

From a post called “Red Sox would like Joe Kelly to diversify his mix“, Tim Britton relays Kelly’s newest prescription for success, handed down by the manager.

MINNEAPOLIS — A day after he was shelled for seven runs in just 1 2/3 innings, Joe Kelly sat down and reviewed the ugly tape with manager John Farrell and pitching coach Carl Willis.

The verdict? The same as Farrell’s been saying really since Kelly was acquired from St. Louis last season: The right-hander should be throwing his curveball more.

“I still contend and strongly believe that his curveball is a major weapon that’s got to be used in his pitch mix,” Farrell said. “You look back at the Texas game: He made a very tangible adjustment after three innings of work when he went to his curveball more than his slider and slowed them down and had some quick and efficient innings. It’s part of the education process of who Joe is as a pitcher and what makes him most effective.”

This might be the weirdest road map of them all. By whiffs, his curve is his worst non-fastball when compared to the league average by whiffs.

It is his best ground-ball pitch. But Joe Kelly’s 52% career ground-ball rate has been his best statistical feature other than fastball velocity. Is this really the final step?

As Farrell points out, the curve is his slowest pitch, and by using it more, he can stretch the possible velocities hitters will see from 80 mph to 96. That might benefit his sinker and fastballs more than another tick of velocity would. And it could work better than the new slider, or the high four-seamers.

Mostly, throwing the curve more might work because there’s a hint of a possibility that Kelly can get the curve over inside the strike zone, which hasn’t been true of his other pitches over time. Look at the zone percentages of his different pitches, indexed to the league averages of each pitch, and you’ll see he can’t command his secondary stuff.

  Pitch Index Zone%
2015 FA 124
2015 FT 106
2015 CU 95
2015 SL 70
2015 CH 30
Total FA 122
Total FC 104
Total FT 101
Total CU 90
Total CH 83
Total SL 74

If your changeup has good shape and velocity, but you only hit the zone with it with one out of every eight thrown… then your changeup isn’t much use. They’ll stop swinging at it.

So there you have it: stealing strikes with the curve ball is what will help Joe Kelly make good on his promise. Either that, or we’ll all have to go back to the drawing board.

Thanks to Jonah Pemstein for finding league average zone% by pitch types.

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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Caveman Jones
Caveman Jones

He’s also on his third pitching coach in the last 11 months. And didn’t start at all in college. That arm is easy to dream big on.


And he’s had to adjust to working with four different catchers already this year, none of whom are named Molina.

Still, I gotta wonder if Eno’s headline will still be valid five years from now. Wouldn’t be the first guy with super talent not to put it all together.

Cool Lester Smooth
Cool Lester Smooth

But he also sucked while working with Molina (and, more importantly, Dave Duncan), haha.

Shirtless George Brett
Shirtless George Brett

Duncan left St Louis after the 2011 season when Kelly had just finished his first season in AA. I realy doubt they worked together a whole lot.


That’s what he seems like to me. Franklin Morales type, but with a slightly higher floor.