You can see how Cahill is able to generate so many groundballs; he throws his sinker a pretty often, and the pitch gets a lot of downward movement. His off-speed stuff has been effective, and the swings (especially out of the zone) and misses are part of how he's increased his strike-outs rate. If he's throwing strikes at the knees and getting ahead in the count early (and thus able to throw the change and curve out of the zone), it might be a tough day for the Orioles' batters. Arrieta:
Arrieta has used his fastball quite a bit. It's an above average pitch, getting a little bit of sink and some tailing action, but he's sometimes left it up in the zone too much so far. The breaking pitches both look good, but he's not getting as many swings and misses on them as one would expect - perhaps because he's not getting the ball down enough. The change-up, on the other hand, is generating some whiffs - even though there's not much separation velocity-wise from the fastball and it's a relatively straight pitch. Whatever works, I guess. I think Arrieta has an above average repertoire, if he can improve his command.