It's tough to say, but I think Bo had it easier. The season prior to the Callahan/Cosgrove meltdown, the Huskers were 9-3 in the regular season. They finished first in the Big 12 North. They lost to #8 OU 21-7, then lost to #10 Auburn 17-14 in the Cotton Bowl and finished at 9-5. Championship games and Bowls are not automatic wins. The can be tough. And not to mention, it took a game winning FG with :23 seconds left for #5 Texas to beat the Huskers during the season. I think Brandon Jackson coughed the ball up which helped ruin the upset. Had the Huskers won, they would have gone into that CCG 10-2!
The next season, after a scary 4-1 start, the unbelievable fallout happened. So they finish 5-7, there's chaos everywhere, coaches get fired, bring in Bo to right this ship!
So I think Bo was basically taking an 8-4, 9-4 kind of team that fell apart emotionally, and got them back to 9-4.
To take a 9-4 team and make them better than that is a little more difficult.
Couple interesting points here...Did you know? (Or maybe forget)
The season the Huskers finished 9-5 with Callahan, the 5 losses were by a combined 56 points. The biggest lost was by 18 points (#4 USC)
The season following, when the Huskers completely fell apart under Callahan, they were ranked in the AP for 6 weeks!
During Bo's first season, at no point were the Huskers ever ranked!
During Bo's first season, they had a 3 game losing streak!
At one point during Bo's first season, the Huskers were 5-4!
Also during Bo's first season, they lost to Missouri on Homecoming 52-17, and also lost to OU 62-28
To get to 9 wins, the Huskers went on a 4 game win streak to end the season (including bowl game) against 4 unranked teams (KU, KSU, CU, Clemson)