NU Comes up short in big situations
Except when it doesn't. I'm not sure why we cherry-picked games from 2005 - 2015, but those weren't the only "big situation" games in those years. There were several more, several that we won, but I guess mentioning those games doesn't further the narrative that whenever there's a big situation/game, Nebraska fails.
Well, Nebraska doesn't fail every time. That's a fallacy. To wit:
2005 Iowa State - Comes back to tie the game late, sending it into overtime, then beats #23 ISU in 2OT.
2005 Michigan (Alamo Bowl) - Nebraska scores 15 unanswered points to take the lead and stun #20 Michigan.
2006 Texas A&M - Zac Taylor leads Nebraska's version of The Drive to beat #24 TAMU in College Station.
2008 Colorado - Nebraska comes back from a 31-30 deficit on Alex Henery's monster kick, followed by Suh's pick-six to seal the game.
2008 Clemson (Gator Bowl) After trailing 14-3 at halftime, Nebraska finishes the game on a 23-7 run to defeat Clemson.
2009 #21 Nebraska trails #24 Missouri 12-0 heading into the 4th quarter on a very rainy night in Columbia, MO, then erupts for 27 unanswered and the win.
2009 Unranked Nebraska defeats #20 Oklahoma 10-3 in one of the most stirring and raucus games in Memorial Stadium history.
2009 Arizona (Holiday Bowl) - just after losing to Texas in the infamous :01 game, Nebraska shuts out #22 Arizona in a dominating performance.
2010 Nebraska stands toe-to-toe and defeats #17 Oklahoma State in Stillwater, 51-41.
2010 Missouri - Roy Helu sets the single-game rushing record, and Nebraska holds off a desparate late charge by #7 Missouri to win 31-17.
2011 Michigan State - Nebraska dominates #9 Michigan State at home, 24-3.
2011 Penn State - Nebraska travels to State College PA for the first time since a 40-7 loss in 2002, and beats 12th-ranked Penn State at home, 17-14.
2012 Michigan - Nebraska throttles #20 Michigan, 23-9.
2012 Michigan State - one week after defeating Michigan, Nebraska travels to East Lansing, scoring 14 unanswered points to defeat the Spartans, 28-24.
2013 Northwestern - if 2015 BYU is included in this conversation, this game has to be, too. The Westerkatch defeats Northwestern off the arm of Ron Kellogg III.
2013 Georgia (Gator Bowl) An overmatched, heavy underdog Nebraska takes it to the Bulldogs, winning 24-19 with the help of Armstrong-to-Enunwa's 99-yard TD pass.
If we want to make the statement, "In 2007, 2014 and through one game in 2015, Nebraska came up short in big situations," then that's accurate. But in every other year listed in the OP, there were other "big situations" they didn't come up short in.
The best descriptor is that Nebraska is "inconsistent," and has been for a long, long time.