This injury really hammers home that one of the key differences between Powe and Davis is that, while Powe is a better player on a per-minute basis, Big Baby can deliver more minutes.
If forced to pick one, the downside is that Powe is a much bigger risk to go down with a season-ending injury and he might not have it in his knees to be a temporary starter for a month. So, if it's easy to get a Mikki Moore of the scrap heap, you might need to compare Glen Davis to a 75% probability of Leon Powe and a 25% probability of having to rely on a Mikki Moore-type player and not a straight up comparison. The ratio might be 90-10 or 80-20 and technically, for BBD it's probably something like 99-1, but I think you get my point.