I wonder how many of those top 25 games TCU were the dogs?
Tough to say for sure, but I think we can get a proximity by the rankings. They were the lower ranked team in 19 of those games. Overall record of 7-12, 4-2 vs Mid-majors, 3-10 vs power-5.
I found the missing game, Texas 2012 for the win. That brings his Power-5 record to 6-10, which I agreed it was decent, but it's been a total bomb of 2-7 since they joined the Big 12. Everybody will have their own assessment of that. I attribute it to part conference change, which is tough, and part upgrade in schedule, as I said before getting up for a couple top-25 games isn't the same as doing it 4-5 times.....I guess that's the whole anti-Boise argument in a gist.
I assume Petersen will have a similar downgrade in win percentage, though his advantage is getting a program already power-5 established...if that makes sense. Although I think you were wrong about # of top-25 teams he had to face while at Boise. If you look at the same time-frames, because it would be unfair to compare 14 years to 8 years as head coaches, of 2006 (when Petersen became HC at Boise) to 2011 (TCU's last year MWC), TCU played 13 top 25 teams vs Boises 11. TCU 8-5 vs Boise's 8-3..... 3 of those were head2head with TCU winning 2. I'm not saying either are bad coaches, that would be naive. I think they are both fine program builders and both won some games against the big boys, but now they are both in the majors. Let's see what happens.