if i had to just guess/ think out loud, i'd go with possibly a result of:
1) hearing repeatedly about the game being pointless/worthless/needing to be replaced by a skills competition
or perhaps much more
2) a gradual effect from the moving it two weeks earlier...it's probably one thing to get (most of) these guys suited up again 3 weeks to over a month after their last game (/loss...essentially just a month later) to play just one more time...while it might be another to say "yeah, i know your season ended in an extremely disappointing manner for you last week (or two weeks ago or w/e), but we want you to get dressed up again and play immediately in a game which means nothing compared to the one still very on your mind"
...just thinking aloud/throwing out some thoughts there though
least the NBC announcers being honest about how big (or maybe how much bigger) a part Mcgahee was in the broncos success (and not just - ZOMG Tim TEBOW!!)