On Get Up yesterday, Jeff Saturday was asked about the parallels of Bills/Chiefs with Colts/Pats- Manning/Brady, specific to what the regular season games mean prior to playoff games. He said it's still important because you're trying glean information and find weak spots to exploit in the playoffs - you're actually seeing/creating matchups and getting an understanding from actually playing that you can't get from film.
One other thing he said was that when the Colts were on the Bills side (losing in playoffs), they realized that physicality and the run game (what Buffalo has done) were the way they would open up the pass game which was being keyed on.
Foxworth also made the point when asked about the psychological aspect of constantly winning in the regular season then losing in playoffs is that winning consistently in the reg season is better than the alternative of losing consistently. He reiterated the points the reg season still has importance in seeing where they think they can attack you etc. More importantly, that the playoff games were so close, play here or there, it's not like the Chiefs were definitively better than them each time (didn't also mention injuries) and part of the competitiveness and belief that comes in the playoffs is being able to show yourself, and them, that we can beat you based on what happened in the regular season