I finally got around to reading an article that's been sitting in my browser for a few days: Josh Kalk's analysis of pitch sequencing at The Hardball Times from February 2009.
The whole article is very interesting, but the Kalk's comments on Phil Hughes really jumped out at me. Kalk notes that Hughes is "almost exclusively a two-pitch pitcher (fastball/curveball) so he needs both pitches working to be successful." Then he goes on to comment about Hughes' future as a major leaguer:
It seems pretty clear that Hughes just doesn't have the necessary deception yet and big league hitters are recognizing his curve and either laying off the pitch or hitting it hard. It is very possible that Hughes' great movement was enough to fool minor league hitters and up until this point he never needed to properly disguise the pitch. With the Yankees' rotation looking full after their offseason spending spree, it seems likely Hughes will start the year in Triple-A. He is likely to do well there as he has already shown he can get hitters out at that level, but without some tweaks, I would be very surprised if he had a lot of success at the major league level. Obviously, he is a very young pitcher and has a lot of time to make the proper changes, but it can be hard to work on something at a level where you don't really need to use it to be successful.
Kalk wrote that article after the 2008 season. In 2009, Hughes was pushed to the bullpen for most of the season. Pitchers generally add about 0.7 mph to their fastballs when they move to relief, but Hughes added over 3 mph - his fastball averaged 94.7 mph in his 2009 relief appearances, after averaging 91.0 and 91.2 mph in 2007 and 2008, respectively. In addition, Hughes' curve went from average velocities of 71.2 and 72.2 mph as a starter, way up to 77.5 mph as a reliever. And the results were excellent: in 44 relief appearances (51.1 IP), Hughes struck out 11.40 per nine, walked just 2.28 per nine, gave up just 0.35 home runs per nine, and put up 2.1 fWAR.
His 7 starts that year weren't as effective, mostly because of his awful home run rate - 1.56 HR/9. But that increase in curveball velocity suggests that Hughes did make some changes. He may have altered his grip, or tried a new arm angle, or made any number of other "tweaks" to his pitching style. Regardless of the details, the results are the pretty impressive.
This information makes me wonder if Phil Hughes is a good case for giving Chris Tillman a shot in the bullpen. Sure, Hughes is only one player, and he only pitched about 50 innings of high-level performance before he reverted to giving up homers left and right as a starter. But his history matches up well with Tillman's career arch. Tillman shot through the minors with his excellent curveball, but he hit a wall when he reached the majors. His fastball has seemed too straight and too slow to get by major league hitters, and it's possible that his all-too-hittable fastball has failed to set up his curveball in the majors. He tried working with a cutter, but it just wasn't enough.
Maybe it's time to give Tillman a full season to work with a major league pitching coach; maybe it's time to let him experiment with his mechanics and his repertoire at the major-league level without fear of demotion; maybe it's time to start taking steps to realize the investment that the Orioles have put in him. He could have a breakout season, or he could show that he still can't handle the big leagues, but it's worth a try and it makes more sense than hoping that he'll fix himself in Triple-A.