Good question. My standards for a HC are only slightly higher than what Glen Mason achieved here:
1. Own the non-AQ opponents you play. 21+ point margins should be the rule.
2. Average .500 or better in the Big Ten in any 4-year period
3. Keep pace with Michigan, Wisconsin, Nebraska and Iowa. Average .500 against these programs in any 4-year period.
4. Win at least half of your bowl games.
5. Run an program that, off-field, we can be proud of.
6. Publicly acknowledge how competitive the Big Ten is. Publicly sandbag if needed (ala Lou Holtz).
If this can be accomplished there will probably be a couple NYD bowl games and/or conference championship appearances over the span of a 10+ year career. But frankly, a lot of that is left to circumstances outside of the coach's control, and isn't a reliable measuring stick as a result. (Mason, for instance, was quite unlucky to have had his best season in a year that the Big Ten happened to be the best conference in football. Ron Zook, on the other hand, got to a Rose Bowl with the same record in a historically weak year for the Big Ten. I think Minnesota 2003 would have destroyed Illinois 2007.)
As for next year... a Pizza Bowl appearance would actually be a very nice stepping-stone after this fiasco.