He's also proven his knees are terrible and that he still doesn't have a jumper - BBD trumps Powe in both areas.
And Powe has proven he's resilient (has come back from other major knee surgeries in his college career), can rebound far better, finishes around the basket much better, and gets to the free throw line better than most players in the league. And Davis's jumper is vastly overrated based on one big time make. He shot about 38% last year outside of 5 feet. Not saying I'd pay more for Powe than for Davis, but for the money, he might be a better option even with the injury.
If they were both 6-10, then I think the Davis supporters would have a point about Davis's more polished offensive game being a significant upgrade over Powe. However, since they're both closer to 6-6 and will likely forever be career backups (at least on good teams), I'm not sure that it matters all that much if Davis is a little better, particularly if he's going to ask for more money.
The real issue is that the C's have struggled to find a real backup center, so consequently both have gotten minutes at the 4 and 5. If Danny finally gets a real backup 5, there's really (at best) only room for one of them. And given that come playoff time KG is going to play 35-40 mpg, I don't know if it's worth paying BBD even 3 million dollars to play the whopping 10 mpg he'll play in the playoffs. And while you could make the argument that he'd be key if KG went down again, if KG goes down again, so will our season, so it won't really matter.
As for the regular season, as long as the C's get a real backup center, I'm confident that Scal can backup KG until Powe finds his way back.