Percival is not done.
He had 9 straight seasons with 45+ games finished until last season.
His h/9, k/9, and WHIP were all better last season than in 2004...a season in which he still finished as the 19th best fantasy closer. Not good, but certainly not too shabby.
Yes, he had arm surgery and yes he doesn't have the stuff he used to, but his numbers last season aren't as bad as everyone would like you to believe. It'll also be his last season, something I think will work in his favor, as he tries to go out with some sort of decent season.
I think a 3.50 ERA, 1.25 WHIP, and 5 saves is what he'll put up next season. Obviously, not good or even fantasy worthy, but he's not trash either.