First off, on the Barry Alvarez subject...
Barry Alvarez did more for Wisconsin than any Big Ten coach has done for any Big Ten program in the last 20 years. He took a program and made it consistently a contender for the Big Ten title.
Between 1952 and 1989, the Wisconsin Badgers went to 6 bowl games.
Since then, they have been to 12.
Only Big Ten coach to win consecutive Rose Bowls.
One of six Big Ten coaches to go to 3 Rose Bowls.
You take out his first 3 seasons (When he was still working with bad talent left over from the former regime), his record was 107-51-4.
From 1993 to 2005, he had 2 losing seasons. That was basically the best run in modern Wisconsin Badgers football history.
The best thing about Alvarez is that he retired at the age of 59. He quit when he was still a great coach, but when he was starting to go slightly downhill. He retired at around the same age as Bo Schembechler (60), become the athletics director (like Bo), and handed his job off to his former defensive coordinator (Gary Moeller was a defensive coordinator for the scUM from 1982-1986, before becoming offensive coordinator for TSUN between 1987-1989).
What Alvarez did was make Wisconsin a consistent winner for the foreseeable future. And he stepped down before he stopped being capable of coaching the team at a consistent high level, unlike Joe Paterno (4 losing seasons since 2000).
Because of Alvarez, Wisconsin is now the 3rd to 4th best program in the Big Ten. Actually, from the 2000 season till his time of stepping down, he produced more NFL players than Lloyd Carr.
On to other head coaches...
As for Ferentz, well, I personally think he is incredibly overrated. This is sort of like Bret Bielema is overrated at Wisconsin. Hayden Fry was the real great Iowa coach, in my opinion. Better overall record, and he created a tradition of winning. Maybe if Ferentz didn't have as many injury issues, he would be succeeding better this year. But, the bottom line is that last years terrible collapse just looks bad.
As for Joe Tiller, he definitely did a great job of enforcing more winning at Purdue, in the regular season. His teams are 3-6 in Bowl Games, including the Rose Bowl loss. But, in reality, he has gotten his teams bowl eligible in every year sans 2006. So, if that is good enough for Purdue, keep him.
Glen Mason? 32-48 record in Big Ten play. He just wasn't good enough to begin with. He left that program in a mess.
But, in reality, some coaches are meant to stay at those kind of programs. For instance, Ron Zook:
Ron Zook is one of those coaches that wants to spend 2-3 years rebuilding a program to his liking. He seems like the kind of coach that isn't a great gameday coach until he has the players he wants in the positions he wants. He wants total and complete control, and doesn't want to be criticized. Hence, he failed miserably at Florida. He works hard, and recruits well.
I'm not overhyping his recruiting skills. He is selling the University of Illinois, for gods sake. Florida had the 20th best recruiting class in 2002 (Spurrier's last year recruiting). The class went up to #4 in 2003.
Please note that Urban Meyer is a better recruiter and a better coach who can use anyones talent and make it work. And that is what Florida wants.
He will enjoy getting praised for leading Illinois to an 8-4 record (That's my projection. Wins over Ball State, Minnesota, and Northwestern. An obvious punishing loss at the hands of Ohio State). He will take the team to a bowl game, and possibly win.
He will continue to get god worship because, at the University of Illinois, a Top 20 recruiting class and a winning record is good enough. So, why would he leave?
Bill Lynch is "good enough" for Indiana. Team is 5-2. As long as his team takes out Ball State (His former team), they should be bowl eligible. A win against either Wisconsin, Northwestern, or Purdue, along with the Ball State win, pretty much guarantees the Hoosiers a bowl game. That is just straight up good enough for the Hoosiers.
Pat Fitzgerald is the Northwestern Wildcats head coach. He was appointed about 5 to 10 years early. I can pretty much guarantee you that if he can win his out of conference gimme games (Come on man, its DUKE!), and then steal some games from the other Big Ten teams (Made up for it with a win over Michigan State), he can stay the head coach at Northwestern. The Wildcats are one win away from bowl eligibility. That is just good enough for Northwestern.
Do you think Mark Dantonio is going to go anywhere if he brings in winning season after winning season at Michigan State? Maybe. Would it be wise? Probably not. He would be coaching a Big Ten team to winning seasons year after year.
Why do you think Rich Rodriguez decided to stay at West Virginia, instead of going for the Alabama job? He will be adored as long as he runs that "fun to watch" offense going, brings in solid recruits, and has his team in the running for the Big East title every year.
Why do you think Greg Schiano stayed at Rutgers? Rutgers is winning. That is just straight up good enough at Rutgers. Winning seasons are good enough. A bowl game is good enough.
I guess what I am trying to say is that sometimes being at mid tier program that is within a big conference like the Big Ten is good enough, if you win at a level that people want you to win. I've spoken to a Maryland Terrapin fan about their football program, and he absolutely loves Ralph Friedgen. When I asked "Why?", he replied "Our team goes to bowl games."
Why leave a school where you get paid a lot of money and receive god worship for something that would be considered mediocre where you would be heading to?
That is why Jim Tressel has succeeded so well. He has Ohio State roots, and he wins National Championships. Granted, it was in 1-AA, but everyone else they were facing was also a 1-AA team. Meaning, he fought on equal ground with teams in his level, and he was the best. The only teams he really ever lost to went on to become Divison 1-A (Boise State, Marshall, etc.). The guy wins championships.
You look at John Cooper at Arizona State, and he went 25-9-2 at Arizona State. That would almost never be acceptable over a 3 year period at Ohio State, unless the program was rebuilding. That would be three 8 win seasons in a row.
So, for mid tier school head coaches, yes. Once you go from mid tier school to top tier school, you will have more resources to do with as you please. You will have a better chance at winning championships. But, as soon as you start to screw up, you are gone.
Mid tier schools just have better job security.