I didn't get a chance to see Wei-Yin Chen make his Major League debut yesterday - I got home for the bottom of the 9th, so at least I was treated to the extra-innings loss - but I've heard some complementary things about it. Chen's line on the night: 5.2 IP, 7 H, 4 R (2 ER - thanks Mark Reynolds), 1 BB, 6 K, 1 HR (to Derek Jeter, leading off the game). The strike-out figure looks impressive, but I'm not sure exactly what to think given that there were a total of 30 K's in the game (16 by the O's, 14 by the Yankees).
Looking at the Pitch/FX for the game:
Chen's four-seam fastball was 88-92 with some movement, but nothing too extraordinary - seems like an average-ish pitch. He did get a couple swings and misses, and pounded the strike-zone with it though.
The change-up also had decent movement (though a few of them really tailed), and some good results - of the 8 that were swung at, 3 were missed, 2 were fouled off, and 2 resulted in groundball. Chen did a pretty good job working that pitch down and away to righties.
The slider didn't have a great deal of break (didn't seem to drop or cut all that much), but got 3 whiffs on 9 swings. It was his primary off-speed pitch to lefties (he threw a few to righties, but was more fastball-change-up).
There were also a handful of curveballs mixed in; slower than the slider by close to 10 mph and with more drop (though not an ungodly amount). The one batter who actually tried to hit the pitch did not succeed (looks like Chen largely tried to waste the pitch low and out of the zone when he threw it).
So that seems like a reasonable mix of pitches, that a pitcher with good control can do something with. Almost (old) Matusz-like, even (not sure having them back-to-back in the rotation makes a great deal of sense). Being able to (mostly) handle a line-up like New York is solid (though we'll see if he can do it again when they get additional looks at him). Chen looks like he could be pretty darn good as #5 starters go - we'll need to wait to see if there's anything more there (I look forward to actually seeing it live).