I think the 13rd forward thing really changed his view on his role on the team. The wakeup kick in the butt he needed, if you will. His 'warrior' attitude didn't help him nor the team, playing through injuries will get the respect of some of your teammates but that's about it. With the depth we have, having him play on one leg with a banged up shoulder and a hurting hip provides no benefit to anybody. That might have worked on a weak team without depth where he'd still be on the top-6 despite all these injuries. Being forced to sit out, stay fresh and healthy will keep him honest and on his toes. Now as others here, I'm all for giving him some rest for the remainder of the regular season and have him healthy for the playoffs.
Respect to Cooper (for all the criticism he's getting around here for whatever reason). He really pulled this one through. He identified the weak link, decided to go with the best players available and hold Callahan accountable. And voilà it's already paying off (for both sides).
One thing we've seen with veterans and former star players on the top end of their careers, they're all fired up come playoff time. Member Vinny in 2011? 19 points, 6 goals and 3 game winning goals in 18 playoff games. Callahan could be the x factor in the playoffs. At worst he's a defensively reliable depth forward who can be put into the lineup when the opposition crushes us physically and in our zone.