Yeah, that is a tough question to answer. It's one I've been pondering for a while (along with why the double wing isn't used more often..but that's a whole 'nother thread in the making

).
I mean, for a long distance runner, "talent" can refer to the physical characteristics of the person - lung capacity, the ability to absorb oxygen, slow twitch muscle mass, etc.
For a football player, however, it's far more difficult because there are so many physical and mental characteristics that are involved - and these change depending on position and play style.
Of course, asking this question is sort of a means to an end - I've been hearing the phrases "talent gap", "talent level", "we need more talent", etc. a bit too much from commentators, coaches, fans, etc. The frequency with which it's used and the fact that it's so hard to define makes it suspect, I think.
There is something called "talent" - we know it when we see it. But my contention is this: using talent as an excuse or as a comparison is fallacious. Good teams are good because they are disciplined and prepared - and that's something the coaches are directly responsible for.
I've always believed one of the reasons NU was so dominant for so long was their conditioning program. They took guys and just worked them into the absolute best condition possible to the point where they just physically dominated any opponent they encountered (not to take anything away from Osbourn et al, of course - brilliant coaches in their own right).
Perhaps that's the defintion that's needed - nearness to peak physical condition.
Next year, if Calahan is really as good as he's supposed to be, I would expect the Huskers to win and win well. If the offense can't be installed in 2 years, then it's too complicated for college and the coach needs to adapt. If he has to wait for recruits to win, then it's the "talent" excuse.
In the NFL, they might be able to plan for 2-4 years out with draftees, trades, player development, etc. But he's got these kids for only 4 years and at best 20 hours a week for practice. I'm hoping he takes the philosphy Meyer, Hawkins, Petrino and (hopefully) Weis do - design the scheme around the players and not try to fit round pegs into square holes.
As for talent, luckily, the weight room is open all year long.
IRISH!