Choosing between players of relatively equal talent, I'll take the one that knows the system.
One of the difficulties that so many guys we've picked up off the scrap heap have had in getting minutes, IMO, is that not having the system in them as second nature meant they couldn't play much...too many execution errors. Mid-season pickups haven't helped much since PJ Brown, and he was a pretty smart, very, very veteran player in perhaps the easiest spot to pick up in the defense.
On the wing, fitting in the system is equal to talent. There should be a slight bias toward bringing back bench guys that have been cool in the locker room and know the system.
We actually could have used Scal quite a bit last year...like, with KG at center in a pinch. And we were in a pinch.