You can't blame one player for losing a team game
That's a fairly inane statement since one player's fumble, interception, failed pass coverage, or missed tackle can certainly be the deciding play in a loss. Just as a completed pass, a touchdown run or a tackle can win or save a game. Besides his final play Nunn also affected the outcome with his inability to field a punt.
Not quite
that inane. While one player's fumble, interception, failed pass coverage, or missed tackle can certainly be the deciding play, it presumes that the player's team has been error free throughout the game. Put another way, had we not blown blocking assignments, not had other turnovers, not made mental errors on the punt return, not allowed the long opening kick off return, etc., then we would have been leading by enough of a margin that Nunn's fumble wouldn't matter - the lead would have been too large to overcome by Texas at that point.
While there might be cases in which a team plays error-free except for one player's single mistake, I'm hard pressed to think of it. Which means that each error leads to the loss - and you can't blame it on a single player. But for the other errors, that single player's error wouldn't be the deciding factor. When it is, it's due to the fact that the team didn't play error-free up to that point.