How could Miami/tOSU not be getting better and better when they both went in undefeated?And USC lost twice 
first, that's not what he said. usc getting better and better doesn't preclude osu and miami from doing the same.
second, he said it "felt" like usc was getting better as season went along, and they did. they were white hot at seasons end and looked like they could beat anyone, including the 2 that played for the title. doesn't mean usc deserved a shot at the title, but not deserving a shot doesn't mean they couldn't also play competitively with them either.
finally, looking at records and going from memory, i feel the same as
@SFBadger96 . usc started pretty weak, having close games and losing a couple of them. then finished on a tear, beating 5 top 25 teams by double digits. including 2 top 10 teams by an average of 26 points.
conversely, both osu and miami started out very strong, and mostly stayed strong but "struggled" a bit with their top 25 teams faced later in the season.
usc started as a mediocre team and finished as a great team. osu and miami started as a great team and finished as a great team. both can be (and imo, are) true; that usc could have contended with and maybe beaten osu and miami at seasons end, and that usc didn't deserve that chance because they didn't play the whole season as such. it is not disparaging osu and/or miami to say the usc got better throughout the season to the point they could compete with them.