Say what you will about Jake Arrieta, but you never quite knew what was going to happen when he took the mound for the Orioles. Sure, there were probably going to be a good number of strikeouts and walks, but occasionally he put it all together in some impressive outings that enticed fans and had them wondering why he couldn't be that pitcher more often.
Overall, his numbers aren't good. In parts of four seasons with the Orioles, he posted a 5.46 ERA in 358 innings. He struck out a decent amount of opposing batters (6.96 K/9, which had trended up in 2012 (8.56) and 2013 (8.75)) but handed out too many free passes (4.0 BB/9). Arrieta's career ERA is about a full run higher than both his FIP and xFIP, and much of that comes from his strange 2012 season. In 114.2 innings last season, Arrieta's strikeouts were up and his walks were way down (2.75 BB/9). But about 24% of the balls hit against him were line drives, and like the season before, he allowed too many home runs (14.5% HR/FB). Also, out of all major league starters who pitched at least 100 innings, his strand rate of 57.3% was the lowest.
In 2012, the average league pitching stats were:
4.01 ERA, 7.56 K/9, 3.05 BB/9, .293 BABIP, 72.5 LOB%
And Arrieta's line:
6.20 ERA, 8.56 K/9, 2.75 BB/9, .320 BABIP, 57.3 LOB%
So Arrieta pitched the best he ever had -- and performed better, at least in strikeouts and walks, than the league average -- and still had an ERA over 6. Weird.
At his best, Arrieta throws strikes, keeps his pitch count relatively low, and pitches seven-plus innings. But those types of performances were rare while he was in an Orioles uniform. When Arrieta took the mound, anything was possible. He could look like a staff ace, or he could have barely any fastball command -- or any feel for any of his pitches, for that matter -- let alone pitch like a past top prospect. But that was why the Jake Arrieta Experience was/is entertaining -- and terrifying (if he's pitching for the team you root for).
As Joe discussed last week, the O's/Cubs trade makes sense for both teams. The O's, right now, don't have much use for "if" guys like Arrieta and Pedro Strop (also because they're 27 and 28 years old, respectively, and not really prospects anymore). There's no question that both have the kind of dominant stuff to succeed in the majors, if they're able to control it. And as we've learned with Chris Davis this season, surprises can certainly still happen.