Because savage doesn't have a history of missing 40% (or more) of games over the course of a season, Dunn does. Every player will miss a game or two now and then, but missing 40% of a season is a lot, the saddest fact is that he's played in 63% and it is an improvement.
What if Blackburn were to sign a player tomorrow who wasn't from Blackburn, but had shown some promise at a young age before being sold a few seasons ago and subsequently struggled to get onto the pitch. We'd all be up in arms, why should we sign him simply because he's a Blackburn fan and he still attends games? He's a talented player, but he's not fit enough and he gets too many injuries.