It is way too early to be jumping to conclusions about Chris Narveson's rotator cuff injury. The Brewers have not said much of anything about a timetable for return yet beyond his 2-week DL stay, but surgery could end his season. That's not to say it will-- there's a heck of a lot we don't know right now-- but it seems a good time to evaluate the options out there to replace him in the short term, and possibly the long term.
The first option will be taking Narveson's first turn in the rotation on Saturday: Marco Estrada. In his only significant major league time, last season, he threw 41 innings as a starter, and he struck out 33 and walked 10 (that's 7.2: 3:3 per 9 if you prefer the rate version). The results, a 3.70 ERA, were better than anyone could have expected from a replacement. There's no doubt that a similar performance this year would be more than the Brewers could ask for, but the question is, how likely is something like that? In 3 years at AAA before he found a home on the Brewer major league staff, Estrada had a 7.2, 6.5, and 7.4 K/9 rates; each year his minor league walk rate was less than his 3.3 as a major league starter in 2011. What to make of this? His rate stats were pretty solid last year, showing that he can hold his own, but expecting anything near that ERA would be foolish. Batters only had a .270 BABIP against him as a starter, and that number could just as easily be .330 in 40 innings this year. Estrada's a safe option to fill in for a period of time, but if he's the fifth starter for the rest of the year, the Brewer playoff chances could take a significant hit.
The high-upside option is top prospect Wily Peralta, who turns 23 in May. He throws hard, has been a workhorse in the minors, and strikes guys out. The number one question has been his command, and he went a long way towards answering that question in 2011, striking out 9.4 per 9 and walking 3.5 between AA and AAA. In 17 innings so far at AAA, he's thrown 17 innings, struck out 13 and walked 6 (which is a slightly lower walk rate than last year). Peralta is up this weekend but it looks like it might be a short stay. Some actually argued that he should have started the year in the Brewer rotation, but I was happy they stuck with Narveson to get Peralta (who only has about a month of AAA experience under his belt) more time. If it does turn out that Narveson will be out most or all of the year, and they're determined to go with Estrada in the short run, the best course of action would seem to be to drop Peralta back to AAA and let him get some more starts, monitoring his innings, and then promote him sometime around the middle of the season. Facing Peralta every fifth day in a pennant race would scare teams a lot more than facing Marco Estrada.
The next option, who seems to have been disqualified by his high-ERA start, is Michael Fiers at AAA. Fiers is 26 so it's not like he's still at AAA for seasoning. As a starter, he put up a 9 K/9 to 2 BB/9 ratio at AA and then put up a 9.6: 3 at AAA in 2011. He's given up runs in his first three starts but his peripherals are just about as good as ever. This is a guy who doesn't throw hard but is probably something close to an equivalent to Marco Estrada right now. If Estrada struggles and they still think Peralta isn't ready in a couple of weeks, Fiers would seem a logical choice to join the team.
Finally I have to mention Manny Parra. Before anyone panics too badly about "OMG Brewers have no more starting pitching depth", remember that they would still have a guy who threw 166 innings with a 4.06 FIP and 4.39 ERA and was the number 3 starter for a long period of time on a playoff team back in '08. If 4 more pitches get injured and Parra has to go back into the rotation for a while-- well, there are worse 9th starters out there. You also have Tyler Thornburg who could possibly make a jump from AA for a few starts in an emergency.
To conclude, many a solid team has acquired a good starting pitcher at the trade deadline and gone on to become a much, much better team. Looking around the Brewer offensive lineup, it's tough to see where any position could be significantly upgraded at the deadline without moving a bunch of pieces. If the Narv-dog is out for a long time, maybe the Brewers will go shopping once again for another piece to make a playoff push.
I think I'm directing this piece towards a fan who might be panicking, even though I haven't read any Brewer fans who are panicking at all about losing Narveson yet. If nothing else it's a reminder that the Brewers are well-equipped to lose a starter, and we shouldn't have to change our overall expectations for this team now that the fifth starter is down.