Dave Gershman continued his excellent scouting series over at Beyond the Box Score with this piece on how to scout first basemen. He basically covers all the points you probably know (first base is a last resort, bat has to be good, etc.), but I found a couple of things worth highlighting.â†µ
First of all, he makes a great point about power at the position. Basically, a first baseman has to have the potential to hit 20 homers a year to stick at the position. To me, that's the biggest reason the Astros soured on Brett Wallace. We can debate his power potential all day long, but if the team doesn't think he can stick there with his power, he's not going to play.
That's why the addition of Jonathan Singleton was both good and bad for Houston. Singleton has the power to excel in that position, but not the versatility to play other positions. If he were doing this as a right fielder, say, he'd be much more highly regarded and probably wouldn't have been traded.â†µ
But, he's still an impact bat. The fact that he can only play first base is why the Astros were able to get him (ditto Brett Wallace). Now, they can only hope he continues to hit.â†µ