Coming into the season two members of the A’s youthful rotation were particularly exciting to watch. Trevor Cahill and Brett Anderson were both top prospects and linked by a host of similarities, both were just 21 years old to start the season, had never pitched above AA and had the rare combination of good ground ball and strikeout numbers. Both pitchers struck out over 8 batters per 9 innings and got over 50% ground balls per ball in play at every level in the minors coming into this year. The big difference is that Anderson combined those skills with excellent walk numbers, while Cahill’s were poor.
That difference as translated to the bigs. Anderson is having an amazing season. By FIP he is the 10th best starter in the AL, an amazing feat for someone of his age and experience. Dave C. and I have each profiled him already (here and here), so I will turn my attention to Cahill’s season.
His ground ball rate is solid (over 47%), but his walk (3.6 per 9) and strikeout (4.6 per 9) numbers have been bad. In fact his K/BB ratio is second worst (again to John Lannan) among qualifying starters. Here is the movement on his pitches.
Like many ground ball pitchers Cahill throws a lot of fastballs (almost 70% of the time), and the problem is he has not been very good at getting them in the zone. His fastballs are in the permissive pfx zone 50% of the time, compared to the 55% for the average fastball. This is one of those things that seems like a small difference but is not. The variation is fastball zone percentage is narrow, so 50% is quite low, and over the course of the whole year those extra balls really pile up.
Cahill has the stuff. His two-seam fastball induces lots of ground balls (55%) while getting an almost average whiff rate (13%) and his good changeup gives him a solid option against lefties. Although this has been a rough year he is very young and with improvement in his command he will be a solid pitcher.