If you take a quick look at Trevor Cahill's 2009 stats from, say, Yahoo! Sports, you probably would come away thinking "It's not great, but he did okay for a 21-year-old."
Cahill went 10-13 with a 4.63 ERA...something like a No. 4 starter.
However, a deeper look reveals a season built on luck rather than skill, and some serious problems for the righty.
Cahill had a 5.33 FIP, 0.70 runs higher than his ERA. His xFIP (4.92) and tRA (5.39) also grade out poorly. All three metrics, which, if you've never heard of them before, are essentially luck-adjusted ERAs, are much higher than Cahill's ERA.
So what does this mean.
Cahill got lucky.
A quick check of Cahill's BABIP confirms this, as his .276 mark is likely not sustainable and will probably regress to the .300 range.
For what it's worth, he did a pretty nice job of limiting line drives (just 18.1 percent of batted balls off him were liners),so his BABIP likely shouldn't have been much higher than .300, but .276 is too low to be what he actually deserved.
Cahill, a modest groundball pitcher, likely benefited from the defense of Mark Ellis, Cliff Pennington, Daric Barton, Jack Hannahan, and Adam Kennedy, who are all quality infield defenders, in 2009. Having Rajai Davis and Ryan Sweeney in the outfield to track down flies doesn't hurt, either.
So Cahill was a bit worse in 2009 than it initially appears. But what did he do wrong?
Well, a lot, actually.
Cahill's strikeout rate (4.53 K/9) was one of the worst in the majors, and his walk rate was rather high (3.63 BB/9) as well. This led to a horrible 1.25 K/BB ratio.
For a pitcher who relies on a sinking fastball, Cahill struggled to keep the ball in the park last year, allowing 27 home runs for a 1.36 HR/9 rate. That's far too high, especially in a big ballpark like the Coliseum.
The three things a pitcher has the most control over are walks, strikeouts, and home runs allowed, and Cahill fared poorly in all three of those in 2009.
So what exactly caused the statistical struggles?
The biggest culprit is that 90-mph sinker Cahill throws. It's a good pitch, but he threw it 70 percent of the time last year, so batters just sat on the pitch and bashed it around. According to Pitch Type Linear Weights, the pitch was 16.3 runs below average on the season. Yikes.
Cahill's second offering, his changeup, was 3.9 runs above average, but that doesn't come anywhere close to undoing the fastball's damage.
In the minors, Cahill was praised for his excellent curveball, but he only threw it 3% of the time in his rookie year, and because of this underuse, it got hit hard, costing Cahill an additional 1.2 runs. He has to ramp up that pitch's usage if he's ever going to be successful.
The two things that Cahill must improve to achieve consistent MLB success are his mechanics and pitch selection.
He has a somewhat awkward finish to his delivery, landing stiff on his front side, that causes his pitches to drift to the right. He almost never was able to locate anything inside to lefties or outside to righties because of these mechanics.
Getting a more consistent, rhythmic delivery would help him improve his command, which would improve all his statistics.
His pitch selection needs to get more even as well, as he needs to lay off the sinker somewhat and work in the curve more.
He threw his changeup 19.4 percent of the time in 2009 and had success with that, so it seems the problem is entirely related to the overuse of the fastball relative to the breaking pitches (he also throws a slider which cost him three runs in 2009).
Given that Cahill turns 22 in March and still has never seen Triple-A, I think a demotion to Sacramento to work on these two issues would do him some good.
After all, the A's aren't planning on contending until 2011, so there's no need to worry about the present in 2010.
Let Cahill get 10-15 starts in Triple-A, dust off the curveball, and try some mechanical adjustments, and when all that's sorted out, bring him up for the second half of the year.
It might hurt the club a bit in the short term, but it could do some good for the prized righty and his team in the long run.