Just a few years ago, Homer Bailey was the #2 pitching prospect in baseball. He threw breathtaking heat and had a killer curve ball--or so scouts raved. But after making his debut in 2007, Homer is still fighting for a rotation spot entering the 2011 season. There's reason for optimism: his peripherals showed tremendous improvements last season, and he's still doesn't turn 25 until May. He is out of option years, so he has a leg up on Travis Wood and Mike Leake in terms of making the 25 man roster...my guess is that he debuts in the rotation. So let's look at what he throws and when he throws it.
Pitches
Bailey throws more pitches than I realized, which makes him more interesting to try to tease apart than anticipated. He throws a two-seam and four-seam fastball (though he seems to prefer the four-seamer). He also throws a slider (which you probably knew, but I didn't), as well as that curveball. One interesting thing I found (well...I found the picture, Mike Fast helped me ID the pitch) is that he at least occasionally throws a spiked curveball, even if he usually uses a more traditional grip.
He also throws a splitter, which he learned from Justin Lehr in AAA. He used to throw a circle change, but I have not been able to find photographs since 2009 of him throwing it. MLBAM thinks still he does, but it's entirely possible that those change-ups in the graph (purple squares) could be misclassified splitters. In fact, given all the hoopla about his splitter a few years ago, I'd be willing to bet that a majority of the change-ups are splitters. Functionally, they do the same thing...but it'd be nice to know. Anyone?
There are also some interesting "aberrations" in how pitches are classified. There are some odd "curveballs" that cluster with the slider, and probably are mis-classified sliders. Same goes for those three "two-seam fastballs" in the slider cluster.
Velocity
At this point, his fastball seems to peak around 96-97 mph, but last year averaged 93 mph. That's down 1 mph from 2009, but up 1 mph from 2008. My guess is that we're going to see 93 mph from him this year, but I don't know--it just hasn't been consistent.
As MLBAM classifies them, his splitters come in at 88.5 mph while his change-ups come in at 87 mph. As discussed above, this may well be just one pitch, and I'll group them together in the discussion below. There's a lot of variation in the spin angle on his slider (which I'm seeing in a lot of pitchers), but they are thrown at ~85 mph. And finally, you see his curveballs in the mid to upper 70's.
I had no idea what to make of the "curveballs" with a spin angle from 300-360 degrees. I asked Mike Fast, who I have leaned on enough that he practically should be a co-author (mistakes are mine, though, not his). He thinks they are most likely either splitters or sliders--the closer they get to 360 degrees, the more likely it is that they are sliders.
Outcomes
| Pitch | Use% | Strike% | GB% | Whiff% | LgWhiff% |
| Four Seamer | 61% | 69% | 40% | 8% | 6% |
| Two Seamer | 7% | 69% | 33% | 9% | 5% |
| Slider | 10% | 56% | 44% | 13% | 14% |
| Curve | 12% | 59% | 52% | 7% | 12% |
| Splitter | 3% | 46% | 40% | 4% | 16% |
| Change-Up | 7% | 64% | 58% | 13% | 13% |
The vast majority of Homer's pitches are fastballs, and those are the pitches that he throws for strikes most often as well. His four-seamer has a reputation as being a fairly straight pitch with relatively little movement, but he gets above-average whiff rates on it as well as above-average (for a four-seamer) ground ball rates. It clearly was working well for him last year.
The two-seamer seems mostly for show. While it did have a good whiff rate, this is based on a relatively small sample (130 pitches, of which only 67 induced swings), and so I am a bit wary about interpreting that number as a strong positive. Furthermore, as a "sinker," it's ability to induce ground balls was terrible. If anything, my guess is that it works when thrown rarely, but increased usage would result in decreased effectiveness.
If we assume that those change-ups are mostly splitters, then his splitter seems to do a great job at inducing ground balls and gets at least league-average swing-and-miss rates. His slider also seems solid in these data. I am frankly surprised at the curveball. While it seems to induce a good share of ground balls, it had a well below-average whiff rate despite being used only 12% of the time. I had always thought of it as one of his better pitches, but if anything I'd probably rank it 4th behind the four-seamer, splitter/change, and slider.
Approach
| vs. RHB | Opening Pitch | Two Strikes | Full Count | Behind |
| Four Seamer | 66% | 56% | 69% | 77% |
| Two Seamer | 6% | 3% | 5% | 8% |
| Slider | 11% | 16% | 6% | |
| Change-Up | 9% | 5% | ||
| Splitter | 4% | 3% | ||
| Curve | 13% | 14% | 15% |
The major difference you'll see against right-handers throughout the count is that Bailey will rarely start a hitter with his splitter/change-up. But he will throw that pitch (or those pitches) about 10% of the time when he's ahead with two strikes. He also increases his usage of the slider in those situations. As the balls start to mount, he starts to avoid the splitter, but will continue to throw the curveball even in full counts. If he's 3-0 on a right-handed hitter, you know that you will see a fastball.
| vs. LHB | Opening Pitch | Two Strikes | Full Count | Behind |
| Four Seamer | 71% | 50% | 62% | 33% |
| Two Seamer | 6% | 5% | 3% | 11% |
| Slider | 11% | 3% | ||
| Change-Up | 4% | 20% | 7% | 11% |
| Splitter | 3% | 4% | 3% | 11% |
| Curve | 13% | 10% | 17% |
No big surprises here. Against lefties, the biggest difference is that Bailey increases his use of his splitter/change and decreases his use of the slider and curveball. He never started a left-handed hitter off with a slider in 2010 (assuming no misclassifications). And when ahead and with two strikes, he went to his split/change almost a quarter of the time. Interestingly, when he has a 3-0 count (Behind), against left-handers he will still throw his split/change almost a quarter of the time, which is a stark contrast from his fastball-only approach against righties in that situation.
Conclusions
Like with any of these reports, I'm reluctant to make many strong conclusions--I'm basically just describing what he does, rather than trying to evaluate how effective it is. The latter is well beyond my skills, and you can debate how well anyone can do it with pitchf/x alone. I do think it's interesting that despite all the hoopla about his splitter and curveball, Bailey relies on his fastball more so than any of the "big 3" Reds pitchers. And last year, at least, it was pretty effective for him, as he achieved the best strikeout rate and the lowest walk rate of his career. The whiff rate on his fastball has increased over the past three years, from 4% in 2008 to 6% in 2009, and then finally to 8% in 2010. If he can continue to get good strikeout rates on his fastball, I think good things are in store for him this season.