Mavric's win total stats are correct, but Bo lost a fair amount to lower ranked teams, (at the time of the game), which is what you're remembering.
2009:
#15 Nebraska loses to unranked Texas Tech - Tech lost two early games to #2 Texas and #17 Houston so they were unranked when they played us but they finished 9-4, won a bowl game and ended up a ranked team.
2010:
#9 Nebraska loses to #18 A&M - A&M finished the year 9-4, ranked ahead of us and three of their losses were to teams that finished in the Top 20
2011:
#17 Nebraska loses by 28 to #20 Michigan - Michigan finished the year 11-2 and won the Sugar Bowl
2012:
#16 Nebraska loses to unranked UCLA - UCLA was unrakned in Week 2 but got to 9-2 and ranked #15 in the country before losing back-to-back games to #7 Stanford at the end of the year
#14 Nebraska loses by 39 to unranked Wisconsin - This was ugly but Wisconsin was the B1G Champion* that year
2013:
#25 Nebraska loses to unranked Minnesota - Another ugly one but Minnesota did get to 8-2 and ranked a couple weeks later before faltering down the stretch.
2014:
#11 Nebraska loses by 35 to #22 Wisconsin - Wisconsin did finish the year 11-3, ranked #13 and beat Auburn in the Outback bowl
#21 Nebraska loses to unranked Minnesota - Minnesota was 8-3 and ranked after they beat us - four of their five losses were to Top 15 teams