Scott Sizemore injured his knee to an uncertain degree. He'll have an MRI on Monday to try to figure out how bad it is.

The list of players on the 40-man roster with some ability to play third base looks like this:

• Adam Rosales
• Josh Donaldson
• Eric Sogard

That's not an inspiring list. PECOTA has Sizemore projected for a .268 True Average, well above 2011's major-league average for the position (.257). Rosales, Sogard, and Donaldson, though, all come in below, at .247, .253, and .252, respectively. Over a full season, based on last year's True Average and True Runs table, that's something like a 15-run difference with the bat. I don't presume to know what kind of defensive hit or gain you get from losing Sizemore, though one would think that Donaldson, at least, would not have the most impressive glove at the spot, converted catcher that he is. (Perhaps his arm, assuming it's relatively strong, can make up for it a little?)

Non-roster candidates aren't much more exciting. I think Wes Timmons is the only player with third-base experience in camp, and as well as he hit in Sacramento last year (.321/.432/.442), and as much as his on-base percentage is pretty well in line with his career figures, his lack of power is uninspiring, and you'd figure someone would have given him a shot already if he were really all that. Instead, he's 32 and a half and the kind of player who gets a major-league shot only if all the other third basemen on the roster go on strike. (And even then, I wouldn't be entirely shocked if Stephen Parker or even Josh Horton jumped over him, little as they played in Sacramento last year.)

If this injury is such that Sizemore will be out for, say, four weeks from today, leaving him in a position where he's just a little behind in getting ready for the start of the year, then presumably Oakland will cover the spot with one of the utility infielders, and the other, the loser of the utility battle, will make the team as the actual utility infielder until Sizemore is back. If Sizemore is out for a substantial period (just to pick something: say he's not expected back until June or July), then maybe Donaldson gets a chance to actually start for a half year and show that he can be a major-leaguer. (Odds are he can't, but you never know.)

The other possibility as mentioned by Susan Slusser is the trade market. Albert Callaspo is reportedly available from Anaheim, what with Massive Mark Trumbo moving over to third base. Slusser suggests that the Angels could take one of Oakland's spare outfielders, but I don't know. They don't even have room for Mike Trout as it stands. What do they want with Seth Smith? (They should want Smith as an upgrade over Vernon Wells in left field, or even as a platoon partner to allow Wells to just mash lefties. Wells's split isn't much bigger than the league average, but he's still got a .288 TAv vs. lefties against .258 vs. righties, so combined with Smith, the Angels could build themselves quite a hitter. Anyway, "should" and "do" are rather frequently not the same thing.)

Callaspo, for what it's worth, has a PECOTA projection of a .264 TAv, so the theoretical drop-off from Sizemore would be virtually nil. FRAA has liked his glove-work in the past, including a whopping +15 last season. He's due just over $3 million this season, and has one more arbitration year left, so he's being paid under the open-market value of his likely performance.

Billy Beane would presumably not be giving up actual future assets for Callaspo, so in terms of fielding a respectable team, I wouldn't find myself terrifically upset with such an acquisition were Sizemore to miss a lot of time.