2005, hmm. I don't even remember what he did in 2005 actually. First thing that came to mind was that horrible Dudley Boyz/Taker feud, but that was in 2004 if I remember correctly. The problem with using Taker to put guys over is that the Mania undefeated streak loses its drawing power. Ofcourse he can lose here and there, like he did to Orton. He probably should have jobbed more from 2004 'till now. Was not a fan of him ending Punk's momentum as the heel champ (in 2009?).
I'd actually like to see a Taker heel run. He's always been a great heel. Hasn't been one since 2002 though. Heel Taker in 2005/2006/2007 etc -> Taker/Cena anyone?