who is the 4th? It's really not even 3 unless you consider PSU, but given they've been in the league for more than 25 years and won 2 championships, one of which was 25 years ago, it's a bit of a stretch to say they belong in that group.
As for OSU, they didn't have their program blown up when we were winning championships. We didn't play them in 2009 or 2010 but we had a losing record in 2009 (still beat uofm that year though) so how much did that really help? From 2011 to 2015 we were 3-2 against the Buckeyes - for two of those wins, the Buckeyes were undefeated and ranked #2 and #3 in the nation. They finished those years ranked 10th (only 2 losses) and 4th (1 total loss).
So Dantonio has won 3 B1G championships and for 2 of them he beat #2 or #3 ranked OSU teams late in the season - one of them at Columbus the week before they went to ann arbor and won by 29. The other in the B1G championship game (you've heard of that game, right?) coincidentally, they won in ann arbor that year too. Also, during that stretch, in the 2 years they beat us they finished ranked 2nd and 4th nationally. So I'd say no, their program wasn't "blown up." History and facts never were your strong suit, were they?
So really, at best it's 2 (but really mostly just ufom), not 4 of our competitors that had their programs "blown up." If facts matter, what you really have to wonder is whether uofm's "comeback" is a function of what's happening in East Lansing and to a lesser extent what happened in Happy Valley. Harbaugh hardly deserves credit for the wins - the combined record of the MSU teams Harbaugh has beaten is 14-20 which further underscores the criticism that he can't beat good teams. Obviously, he's not winning championships but right now, it looks like his elevating uofm to upper 2nd tier status in the B1G is just like a product of being a "consistently average" coach during a time when at least half his competition for 2nd place has fallen on hard times.