My guess is what another poster above stated, that he probably didn't get any interest from other teams which is why he was delaying.. because everyone knows that arm is a j0ke now and everyone knows that the Broncos defense literally lifted Manning up onto their shoulders and carried him to another Super Bowl... never seen a QB do less in the postseason than this latest run by Manning
I also bet he desperately wanted to latch on to another team solely to keep padding his career records... i would be anything that he's legitimately worried Brady will catch up and surpass his yardage record and some others.. Brady would have to have a hell of another 4 years to catch the TD record.. i think that's less likely, but with Gronk, Edelman and hopefully some additional weapons, i think he'd only need to score around 32 or so TDs a year which is very doable