Lance Berkman may not miss opening day, which would mean that this post is pointless. Based on what I can glean, 2 - 5 weeks is an expected recovery time for his arthroscopic surgery. On the conservative side--and that seems like a good approach with your team's best hitter--Berkman could miss the opening series and perhaps even a couple of weeks of the season. And, by the way, Bernardo Fallas has a well done blog piece on Berkman's arthroscopic surgery; as it turns out, Fallas got to know a bit about knee surgeries from his days covering the soccer beat. For those who foresee the worst in Berkman knee surgery, take heart in this passage from Fallas' posting:
A traumatic event certainly could have caused Berkman to have them in the knee.
If this is the case, and given the injury was not serious, a safe bet would be that they are cartilaginous.
Another, decidedly less popular possibility is an arthritic knee, something Berkman has not (I repeat has not) been diagnosed with.
It's common to think that AAAA players are major league wash outs. But Shelton's major league history isn't all that bad. In 1,044 ML plate appearances, he has a 110 OPS+. And in his Andy Warhol five minutes of fame, when Shelton was being compared to the next Roger Maris, he posted a 131 OPS+ in 431 plate appearances for the 2005 Tigers. Shelton posted a .360 OBP that year, and has a .345 average OBP in the majors. Blum's OBP is...oh, let's not get into that.
Shelton's minor league career average OPS is .880. As far as platoon possibilities go, consider his minor league career OPS versus LHP: 1.015. Last year Shelton's AAA OPS was .891. His OBP was .389 and his SLG was .502. Against LHP last year, his SLG was .611 and his OPS was 1.076. It makes you wonder why Shelton hasn't gotten more chances. And I think the answer is that he is suited for 1st base and DH. But, if the Astros need a first baseman, even for a couple weeks, they have him.