Because it is the first time that you ever had 3 of them and you now have a weird situation. Alabama just beat the number 1 undefeated team and won the SEC so they are clearly one of the top 4 teams. Michigan beat the number 2 team (to knock them to 7) and won their conference undefeated. Washington similarly had a schedule you cannot really argue with. Florida State meanwhile had its best win early, which is the worst win out of the teams ahead of them, and lost its starting QB so again as stated in the requirements, they took the status of Florida State as it was currently made. Granted all this will fix itself next year but I understand the decision.