Brian Matusz coming off the disabled list was supposed to be a happy event. The Orioles were upgrading their rotation by adding perhaps its best member. But so far, that hasn't been how things have worked out at all. Matusz has a 5.60 ERA after four games, and that's pretty consistent with how he's pitched.
While never a huge strike-out guy, Matusz is K'ing just 5.6 per nine this year. His control has been not so good, with a 4.6 BB/9. And when he has thrown strikes, batters have hit them. The fastball, which is now ~87 mph instead of 90, is producing just a 5% whiff rate (over 11% last year). On top of the velocity loss, the pitch isn't moving quite as much as it used to. Given that, it's not surprising that his change-up has been less effective, with the whiff rate falling from 32% to 19% and batters in general being better about laying off the pitch. A healthy Brian Matusz who can spot and mix his pitches might be able to survive in the majors with an 87 mph fastball, but I'm not sure this current version can. His FIP is 6.18. His xFIP is 5.43. And at this point Chris Tillman or Brad Bergesen might put the O's in a better position to win on any given day.
Things may pick up as Matusz gets in more work, but what if they don't? Since 2000, there have been 26 left-handed starters (with at least 500 IP) whose fastballs have averaged 88 mph or below. Their overall stats in that time frame:
Those are not particularly great numbers, and if that's all the O's can get from Matusz then I don't think the team will be all that excited. And keep in mind, most of the included guys got to the big leagues with lower velocities, so there's a bit of selection bias in that they wouldn't have made it with 87 mph fastballs unless they could pitch well enough that way. And they tended to induce groundballs a little more often than Matusz does, which leaves him a bit more vulnerable to the longball. But I think it paints a reasonable picture of what to expect from Matusz if he doesn't turn back into his old self on the mound.
Perhaps Matusz still isn't 100%, but I believe Buck Showalter was previously quoted as saying that maybe his velocity will never come back. Maybe if it won't he'll turn into Mark Buerhle. Or maybe he'll turn into Darrell May. In any case, Matusz's season reminds us of the fragility of pitching prospects, and more specifically why I would have preferred picking Justin Smoak over him in the 2008 draft. In 2009 and 2010 that looked wrong, but suddenly Matusz chances of being a consistently league average starter are looking a little bit longer (though I still think he'll be OK - it's only 17.2 IP afterall) while Smoak is hitting .254/.356/.482 in Seattle - and his 135 wRC+ would lead the Orioles. Predicting the future is hard, and we still don't know what it holds for Matusz - but a 7 K, 0 BB performance while at least touching 90 his next time out would sure make me feel a whole lot better.
Stats: ERA, FIP, xFIP, K/9 & BB/9, PitchFX