In two years at Tulsa-
2007 losses:
Oklahoma 62-21
UTEP 48-47 (the defense lost this game....UTEP did score 40+ 5 times in 07)
UCF 44-23 (that UCF team went 10-4 and lost to TEXAS 35-32....they were pretty darn good).
UCF 44-25 (ditto)
2008 losses:
Arkansas 30-23
Houston 70-30 (again, the defense didn't help by giving up 641 yds and 70 pts. Tulsa also had 5 turnovers).
ECU 27-24 (was a very up and down ECU team that was very capable of beating anyone...beat Va Tech and WVU early).
It doesn't matter who you are, you're going to have off games and you're going to get slowed down occassionally. Look at Florida in the BCS title game last year. They had averaged 51 points in the 8 games leading up to the title game, scoring less than 40 only once. Yet they were held to 24 points by a not-so-special OU defense.
The thing to remember are the averages for the year. Sure, there were a handful of teams that slowed them down (or against they failed to execute, or against who they had 5 turnovers, etc). But when you average what Tulsa averaged, you were very successful.