Put simply, Jake Arrieta has been baffling this season. In one outing he’ll rack up the strikeouts and look like an ace. His next time out he’ll get shelled — walks, home runs, doubles — you name it. Arrieta gets hit hard at times, and that may be an understatement.
Arrieta’s inconsistency is extremely frustrating, even more so when one of his bad starts happens shortly after he flashed brilliance.
Looking at Arrieta’s season statistics once again adds more frustration to this puzzle. His 2012 numbers improve upon all of his career numbers — and by a wide margin.
In every statistic you would want a young pitcher to improve upon, Arrieta has done so. Strikeout rate? He’s striking out 8.07 batters per nine innings after striking out 5.94/9 in his first two seasons. Walk rate? He’s slashed his walk rate from 4.39 BB/9 in his first two seasons to 2.49 BB/9 this season. As a result, his FIP has gone from 5.08 in his first two seasons to 3.88 this year.
All of Arrieta’s numbers have taken a turn for the better this season except maybe the most important one: ERA. Despite walking less batters, striking out more, and an increase in fastball velocity (up 1 MPH from last year), Arrieta’s ERA has gone from 4.87 ERA in his first two seasons to 5.55 this year.
Sometimes, there are reasonable explanations for a pitcher’s struggles. With Brian Matusz, he lacks the velocity and command necessary to pitch in the majors at this time. As a result, he’s struggling. However, this is not the case with Arrieta.
Arrieta has pitched well. His stuff is sharp. His control is above-average this year. He does lose command of his fastball sometimes, but generally speaking about his season, he’s pitched better than his 5.55 ERA indicates. Unlike Matusz, Arrieta’s “struggles” have a lot more to do with luck and the baseball gods refusing to join his side.
LOB%, BABIP, and HR/FB% are three statistics that, when compared to career numbers, can help us determine whether a pitcher is unlucky or not. Well, you guessed it. Arrieta’s numbers this season in those three categories differ greatly from his career numbers. All three are working against him.
Arrieta’s career LOB% is 68.2%. This year it’s 60.6%. His HR/FB% in his first two seasons was 11.4%, and this year it’s jumped to 12.9%. And perhaps the biggest dagger of them all is his BABIP, which was .280 in Arrieta’s first two seasons but has risen .034 points to .314 this year.
Pitchers with strikeout rates similar to Arrieta’s generally have lower BABIPs. A major jump in BABIP occurring in the same season that Arrieta’s strikeout rate and arsenal has improved simply doesn’t match up.
I had been saying in our forums that, eventually, Arrieta’s ERA and FIP would have to balance out. That’s happened over his last three starts, where he has a 2.35 FIP and a very similar 2.25 ERA. Finally, Arrieta’s luck has balanced out and the results of his peripherals are beginning to show in the actual amount of runs he’s giving up. The baseball gods are on his side. Hopefully for good.
As long as Arrieta continues to pitch as he has this season — the same way that’s gotten him a 3.88 FIP and 3.65 xFIP — he may just become a consistent, #3 starter that the Orioles desperately need behind Jason Hammel and Wei-Yin Chen.