Well, stuff-wise, scouts are saying this guy would be a legitimate #1 pitcher for just about any team. He throws in the low-mid 90's, has a good slider and curveball. He showed in the WBC that he can get good major league hitters out. The "gyroball" thing appears to be more legend than fact, as I've yet to see any definitive proof of it.
The thing that worries me, slightly, and this seems to be something most news reports are neglecting to mention, is that some of Japan's pitching practices would be considered insanely abusive here. For example, Matzusaka threw a 250-pitch, 17-inning complete game once. MLB pitchers don't throw that much in a week. You could, perhaps, make the argument that, since Japanese pitchers are conditioned to throw large pitch totals at an early age, they're not as likely to break down as American pitchers, who are protected and at times coddled to avoid injury. Maybe you'd be right, I dunno. Livan Hernandez says that in Cuba his coach would basically have him complete every start, and throw 50-100 pitches on the side every day, and that it was that extreme regiment that gave him his stamina today.
In my opinion(and I'm not alone on this), the workload makes him a good candidate for arm blowout somewhere down the line. Still, for the next couple of years, I don't see any reason he can't be another Nomo(who, it's worth noting, never had any severe arm troubles).
Jim Albright, who knows more about Japanese baseball than I know about anything, has done some fantastic research on translating their game to the MLB, and predicting how Japanese stars would do or might have done here(he has an article on Sadaharu Oh that is especially excellent). He charts Matsuzaka using his new
pitcher projection method, and this is how Matsuzaka's last two seaons translate to pro-ball(assuming a neutral home park):
2005: 30 GS, 14 W, 11 L, 231.33 IP, 220 H, 19 HR, 63 BB, 238 K, 3.72 ERA, 1.22 WHIP
2006: 27 GS, 14 W, 8 L, 202.67 IP, 177 H, 19 HR 43 BB, 211 K, 3.14 ERA, 1.08 WHIP
Those are pretty good numbers(borderline Cy-Young caliber), and keep in mind, he's only 26.
