Joe Kelly’s Numbers and Joe Kelly’s Numbers

The Cardinals’ pitching staff, obviously, is led by Adam Wainwright, and Wainwright’s curveball is the single biggest reason the team was able to slip past the Pirates in the previous round. Wainwright’s a veteran, and though he can throw pretty hard, he’s not known for his velocity so much as his movement and command. But behind Wainwright, this is a postseason staff featuring a hell of a lot of mostly young heat. Michael Wacha kept the Cardinals alive by nearly keeping the Pirates no-hit. Lance Lynn can run it up there. Trevor Rosenthal’s fastball is the main reason he’s so dominant. Kevin Siegrist and Carlos Martinez can blow hitters away in front of Rosenthal. Shelby Miller and John Axford have big heat, if also big question marks. And there’s Joe Kelly, whose fastball this season averaged 95 miles per hour.

If you’re being honest with yourself, unless you’re a Cardinals fan, Kelly’s probably a virtual unknown. He’s also tonight’s Game 1 starter in the NLCS against the Dodgers, and if you just glance over Kelly’s statistics, you’ll come away unimpressed. If you dig into the splits and isolate his performance as a starter, you’ll come away even more unimpressed. The performance numbers paint one picture of Kelly. The velocity numbers paint a picture quite different. The two different Kellys are somewhat hard to reconcile, but it helps that the same profile exists somewhere else.

Over the last two years, out of 188 starters to have thrown at least 100 innings, Kelly ranks 12th in average fastball velocity, coming in at 94.5. He’s spent a lot of time working out of the Cardinal bullpen, and out of the bullpen he’s thrown a bit harder, but the velocity has still been there in extended stints. The two names on either side of him: Andrew Cashner and Zack Wheeler. Sort next by strikeout rate and the names around Kelly’s are Dylan Axelrod and Tyler Chatwood. He’s struck out a slightly lower rate of batters than Joe Saunders and Barry Zito. Worse still, he’s had Zito’s walks. Kelly’s saving grace — if you look past his ERA — has been that he’s kept balls on the ground. He hasn’t allowed himself to get too hurt, especially in would-be run-scoring situations.

Mentally, we correlate velocity with strikeouts and general unhittability. This is because faster pitches are harder to hit than slower pitches, and we think of 95 as being really fast. For Kelly to miss so few bats, then, is confusing, but what’s going on with Joe Kelly is the same thing that’s been going on with Henderson Alvarez. Alvarez has a live, hard-throwing arm, unleashing sinkers with tail and bite and pleasing aesthetics. On the last day of this very season he threw a no-hitter. It was a no-hitter with four strikeouts and six whiffs. Alvarez’s strikeouts have never matched what we think his fastball should mean, and the fault isn’t so much Alvarez’s as it is probably ours.

Just for a glimpse, here’s an Alvarez fastball:

And now here is a Joe Kelly fastball:

Yep, look like fastballs all right. This season, Kelly’s sinker and Alvarez’s sinker had similar velocities and similar movements. Both were thrown about 70% of the time. Both got similar rates of whiffs, and both got similar rates of grounders. It isn’t fair to say that Joe Kelly is another Henderson Alvarez — they’re of different bloodlines, and Alvarez tends to work more within the zone — but there’s a lot of overlap, a lot of commonality in the profiles. Alvarez isn’t some exception. Kelly isn’t some exception. They aren’t destined to miss more bats; what happens is a consequence of who they are.

Kelly wants balls in play. He wants weak grounders, and sinkers aren’t swing-and-miss pitches as a general rule, even if it looks like they move a lot. And though Kelly does throw other pitches, they aren’t necessarily all that consistent or polished. Sometimes they look fine…

…but it’s easy to throw decent secondary pitches some of the time. Consistency is the issue, and there’s a reason Kelly throws so many sinkers. A few reasons, I guess. He likes his sinker, he likes what it does, and he likes it more than he likes his other stuff.

Kelly was drafted in the third round in 2009 out of Riverside, but he was drafted as a reliever. He relieved throughout his collegiate career, and so becoming a starter in the Cardinals’ system was an adjustment within an adjustment. Kelly’s secondary stuff is probably still developing, and he was drafted on the strength of his power sinker of which he’s still in possession. That’s the foundation, and Kelly’s trying to build around it.

It’s easy to have a skeptical eye upon viewing Kelly’s starting statistics, because they don’t look great past the runs allowed. Take away the plate appearances against pitchers and he had almost as many walks as strikeouts, and that’s the mark of a potential disaster. But in Kelly’s defense, there’s this: according to the Baseball Prospectus PITCHf/x leaderboard, this year 80 starting pitchers threw at least 500 sinkers. Kelly was the only one whose sinker didn’t get taken deep. To the eye, the pitch doesn’t dive, but clearly it does something right. Nobody’s sinker allowed a lower isolated slugging.

What we’re left with is a guy who isn’t as good as his numbers, and who isn’t as bad as his numbers. Interestingly, we know that strikeout potential is there. As a reliever, Kelly has thrown a little harder, but not much, and he’s more or less preserved his same pitch mix. This year, Kelly struck out 13 fewer batters as a reliever than as a starter, in 50 fewer innings. These pitches can miss bats. Kelly just follows a different course as a starter, and perhaps it’s worth noting that his overall strikeout rate was 13% with the bases empty and 19% with runners in scoring position. Joe Kelly might not be a Twin in reality, but he’s damn sure a Twin in spirit.

By shifting on the rubber this year, Kelly has somewhat evened out his platoon splits. He’s prevented runs as a starter, increasing the likelihood he’s a starter going forward, and his secondary pitches could still be further developed. As a starting pitcher, Joe Kelly is younger than his age. But what matters tonight is Joe Kelly right now, and right now Kelly is a lot like Henderson Alvarez. He’s not the dynamo his ERA would suggest, but he’s not necessarily the liability suggested by other numbers, so long as you understand what Kelly’s trying to do. All that he wants is a ball on the ground. Get enough of those and you can have yourself a fine ballgame.