Wait a Second: Half You Seen What’s Jake Arrieta’s Done Since the Break?

Chances are you’ve already heard/read/talked about Jake Arrieta’s performance over the last dozen starts or more. I know I have. And I can’t hear/write/talk enough about it, so I’m hoping you have an equally insatiable appetite for all things Jake.

So exactly how good has Arrieta been since the All-Star break? So good that the single earned run he allowed in 8 innings of work on Wednesday actually raised his second-half ERA. He came into the game with an earned-run average of 0.93 in his previous 11 starts, the best-ever post-ASG mark in baseball history. He came out of the Pirates game with a 0.95 ERA, just behind Kris Medlen’s 0.94 in 2012.

In the 12 starts in question, Arrieta has allowed only 9 earned runs in 85 1/3 innings pitches (just over 7 IP/game). What’s more, only 12 total runs have crossed the plate against him. That’s 1 run per start. Basically, if you give the man 2 runs of support, you’re going to win. Well, sort of. I mean, he can’t throw a complete game every time out, so you’ve got to count on the bullpen for a little support. Perhaps that’s why we saw Arrieta take an at-bat with men on 2nd and 3rd with 2 outs in the 8th on Wednesday.

Probably not a move that’ll be featured in the scrapbook of all-time genius Joe Maddon moves, but the relatively unimpugnable skipper was likely saving bullpen bullets for the upcoming series with St. Louis. And since the Cubs ended up winning, it really wasn’t too big a deal in the end.

Speaking of winning, Arrieta has been doing his fair share. He’s 9-1 since the break and has a league-leading 19 total wins. One more victory will make him the first Cub to reach 20 since Jon Lieber in 2001 and only the second since since Greg Maddux in 1992. In fact, Maddux and Lieber are the Cubs’ only 20-game winners since 1977 (Rick Reuschel).

In looking at some the other numbers, it might seem somewhat strange that Arrieta would be getting better results of late. In putting up a 2.66/2.67/2.84 ERA/FIP/xFIP slash in the first half — certainly nothing to sneeze at — Arrieta compiled 9.10 K/9 and 1.85 BB/9. One would think that those numbers would have improved over the last 12 starts, but the opposite is actually true. Not seismic shifts, mind you, but his respective marks of 9.07 and 2.32 seem to belie the other statistical shifts.

So what changed to precipitate this incredible performance? Well, it’s less about the balls not being put in play as it is those that are. Take a look at the charts below for illustrations of Arrieta’s groundball rate in the 1st half vs. the 2nd this season.



The first thing that jumps out is the overall GB%, which jumped from 50.3 in Arrieta’s first 18 starts to 62.1 in his last 12. You surely noticed the change in the results of the four-seamer as well, a drop-off that would seem alarming absent context. After all, it appears as though the pitcher is getting no grounders on that pitch. In fact, this is because he’s basically stopped throwing the pitch altogether.

Actually, Arrieta has scaled back the use of all of his peripheral pitches to focus on the sinker, which he now utilizes at nearly a 52% rate. And he throws it hard too, at an average of 94.5 mph. FanGraphs ranks his fastball as the best in the game over the 2nd half, ahead of Clayton Kershaw and Matt Harvey. For what it’s worth, Jon Lester’s heater is ranked 4th. His cutter is also rated as baseball’s best this half, but there’s a little more noise in that data.

Due to the difference in pitch tracking across different services, you might find Arrieta’s nasty breaking stuff classified as either a cutter or a slider. Regardless of its name, the pitch is devastating; thrown in the mid-90’s it’s basically just unfair. And here’s the thing: Arrieta is throwing harder now than he was at the beginning of the season.


That he’s able to achieve greater velocity on his two main pitches this late in the season is pretty remarkable, particularly when you consider that he surpassed his career-high innings total in mid-August. The velo dipped overall in August, but see where he pushed it back up? That’s right about the time Arrieta exceeded the 156 2/3 he threw last season. Given his dedication to fitness and the consistency of his production this season, I see no reason to believe there’ll be a letup in October.

At this point, I’d say the only things Cubs fans need to worry about are Jake’s throws to first and his skills in identifying music.

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