Corey Kluber gave us Kluberization: the ditching of a bad four-seam for a better two-seamer. Dallas Keuchel gave us The Keuchel Excercise: the turfing of a bad curve for a better slider. Is Jake Arrieta following the Jesse Chavez Legacy? It certainly looks like he’s in the process of a major change in his pitching mix, and it might be what allows him to finally make good on all the promise that he’s shown to date. It should at least help him improve his command.

Jesse Chavez dropped his four-seam fastballs for a cutter, for the most part. That was important because of his iffy command. You need your fastballs for strikes, and look at his relevant career rates on the four-seamer, two-seamer, and cutter, courtesy BrooksBaseball:

Pitch Type Ball Whiffs GB% Fourseam 34.30% 8.29% 26.64% Sinker 32.17% 4.96% 48.18% Cutter 29.82% 9.06% 42.46%

Looks pretty clear that the cutter is a better pitch than his four-seam fastball. And so he’s gone from using the four-seamer 30+% of the time years ago to less than 3% this year. And the cutter is up to 40%, or second-highest in baseball. And his walk rate is at a career-best.

For more evidence that Chavez is using his cutter as a fastball, let’s look at his usage per count. Fastball usage in baseball is highest in 3-0, 3-1, 2-0, 2-1, and 0-0 counts respectively. Four-seamers and two-seamers are used 65% of the time in those counts. Cutters and sliders are used 17% of the time. Chavez uses his fastball in those counts 41% of the time, and uses his cutter 34% of the time.

Let’s look at the relevant fastball rates for our new Jesse Chavez candidate, Jake Arrieta. Here they are over the last three years. (The broadcast team calls Arrieta’s slider a cutter, and so we’ll go with their name for the pitch.)

Pitch Type Ball Whiffs GB% Fourseam 38.08% 6.95% 36.17% Sinker 35.37% 4.79% 46.20% Cutter 36.42% 13.20% 39.66%

It’s not as clean-cut here. The cutter does better than his four-seamer, if not by the same margins. This year, though, the margins have increased — his ball rate on the slider is down below 30%. It certainly looks like Arrieta has begun to follow the path set forth by Chavez:

Pitch Type 27-May 3-Jun 8-Jun 13-Jun 18-Jun Fourseam 25.5% 17.3% 11.8% 23.2% 23.8% Sinker 36.2% 27.0% 31.2% 10.1% 25.7% Cutter 12.8% 26.0% 34.4% 43.4% 32.3%

He’s never used the cutter more than 15% for a season, and now he’s doubling that number regularly all of a sudden. Maybe we can believe his improved walk rate.

But there’s more to it than just raw usage — Arrieta was also using the pitch in fastball counts in yesterday’s seven-inning, 11-strikeout, one-walk win. His first pitch of the game was a cutter, and he threw the cutter on the first pitch against a third of the batters he saw. That’s almost three times higher than his first pitch cutter usage over the last three years (12%) and higher than the league’s first pitch cutter/slider usage as well (17.6%). That trend holds for those last five games, when Arrieta has used his cutter 24% in the fastball counts described above (57% for his fastballs). Not quite as stark as Chavez, but still different than league average.

Of course there are risks with this approach. Dan Duquette banned the cutter from the Orioles’ organization, and it looks like the “baby slider” version of the cutter might have some bad velocity outcomes. Dan Haren, the starter that’s currently throwing the most cutters in baseball, admits that he agrees that the cutter causes velocity loss. Then you have to add in injury risk. Jeff Zimmerman has found increased injury risk among heavy breaking ball users, and even if the ASMI doesn’t agree, there are others that back Zimmerman’s findings.

But, 450 innings into a career that has seen results that don’t follow his upside, and still sporting a fastball averaging nearly 94 mph, Arrieta has velocity to lose and command to gain. Now he’s got his walk rate down to a career best at least partly due to throwing his cutter more often in fastball counts, and he may have that in common with Jesse Chavez. All it took was a new approach.