[Bumped for putting numbers to what we all pretty much understand in our guts --- when a coach is/should be in trouble. Bama Hawkeye]

One interesting aspect about college football is that different schools have differing expectations for their coaches.  At one school, going to a bowl game once might guarantee their spot for years, while at another a single losing season will place the coach on every "hot seat" listing in the country.

This disparity makes determining whether a coach has been successful much more difficult as winning percentage is rather useless.  Instead, we must look at the tradifference, the difference between the coaches performance and the school's traditional level of performance.  

Every coach's tradifference after the jump, including the school with the biggest recent upswing (hint: a wizard did it.)

I looked at three different data points: the school's winning percentage in the last 50 years excluding the current coach, the 25 years before the current coach, and the 10 years before the current coach.  The difference between the average winning percentage for these three periods and the current coaches winning percentage is that coach's tradifference.  

Schoool: Michigan

Coach: Rich Rodriguez

Started in: 2008

Winning Percentage: 0.333

School's Winning Percentage Since 1960 Excluding Current Coach: .742

School's Winning Percentage In 25 Years Before Current Coach: .754

School's Winning Percentage In 10 Years Before Current Coach: .744

Tradifference: -.414

Michigan fans need another reason to hate Rich Rod?  No coach in the Big Ten has had anywhere near the change from their historical level as Michigan under Rodriguez, but you probably didn't need any math to realize that. At least he's run a clean, respectable program.  

Schoool: Minnesota

Coach: Tim Brewster

Started in: 2007

Winning Percentage: .368

School's Winning Percentage Since 1960 Excluding Current Coach: .474

School's Winning Percentage In 25 Years Before Current Coach: .431

School's Winning Percentage In 10 Years Before Current Coach: .529

Tradifference: -.110

Based on these numbers, I can't see any way Brewster keeps his job.  Not only is he substantially worse than recent Minnesota teams, he hasn't even managed to replicate their usual level of mediocrity.  The situation is even more awkward because Brewster replaced Minnesota's most successful coach since World War II, who was fired for not meeting expectations.  

Schoool: Purdue

Coach: Danny Hope

Started in: 2009

Winning Percentage: .417

School's Winning Percentage Since 1960 Excluding Current Coach: .515

School's Winning Percentage In 25 Years Before Current Coach: .468

School's Winning Percentage In 10 Years Before Current Coach: .556

Tradifference: -.096

Danny Hope only has one year of experience, but he needs to improve on his first effort to maintain Purdue's level of success.  Joe Tiller left Purdue with higher expectations than when he entered.  

Schoool: Illinois

Coach: Ron Zook

Started in: 2005

Winning Percentage: .350

School's Winning Percentage Since 1960 Excluding Current Coach: .439

School's Winning Percentage In 25 Years Before Current Coach: .486

School's Winning Percentage In 10 Years Before Current Coach: .373

Tradifference: -.083

Zook is another coach underperforming expectations, even Illinois' relatively meager ones.  I don't expect him to survive the year either, though U of I has obviously tolerated mediocrity in the past.  

Schoool: Nebraska

Coach: Bo Pelini

Started in: 2008

Winning Percentage: .704

School's Winning Percentage Since 1960 Excluding Current Coach: .783

School's Winning Percentage In 25 Years Before Current Coach: .787

School's Winning Percentage In 10 Years Before Current Coach: .677

Tradifference: -.045

Based on this method, no one has a higher bar than the coach of the Big Ten's newest team.  So far, he has done reasonably well and seems poised for a 2010 season that would move him closer to joining Nebraska's long line of successful coaches (Bill who?).

Schoool: Indiana

Coach: Bill Lynch

Started in: 2007

Winning Percentage: .378

School's Winning Percentage Since 1960 Excluding Current Coach: .377

School's Winning Percentage In 25 Years Before Current Coach: .400

School's Winning Percentage In 10 Years Before Current Coach: .310

Tradifference: +.016

On the opposite end of the spectrum, Coach Lynch is actually outperforming Indiana's traditional level of ineptness.  Indiana doesn't seem to care either way.  After all, football season is just a sign that basketball is coming in 3 months.

Schoool: Iowa

Coach: Kirk Ferentz

Started in: 1999

Winning Percentage: .596

School's Winning Percentage Since 1960 Excluding Current Coach: .490

School's Winning Percentage In 25 Years Before Current Coach: .560

School's Winning Percentage In 10 Years Before Current Coach: .591

Tradifference: +.049

Ferentz took over from the most successful coach in Iowa history and improved on Hayden Fry's record.  Of course, that doesn't change his losing record against Northwestern.

Schoool: Michigan State

Coach: Mark Dantonio

Started in: 2007

Winning Percentage: .564

School's Winning Percentage Since 1960 Excluding Current Coach: .527

School's Winning Percentage In 25 Years Before Current Coach: .497

School's Winning Percentage In 10 Years Before Current Coach: .513

Tradifference: +.052

Dantonio seems to be a good fit at MSU.  

Schoool: Penn State

Coach: Joe Paterno

Started in: 1966 (not a typo)

Winning Percentage: .752

School's Winning Percentage Since 1960 Excluding Current Coach: .677

School's Winning Percentage In 25 Years Before Current Coach: .698

School's Winning Percentage In 10 Years Before Current Coach: .693

Tradifference: +.063

This exercise is completely senseless for Joe Paterno.  As the saying goes, Joe Paterno came to cow pastures and founded a college football national power ... that plays near cow pastures.  

Schoool: Ohio State

Coach: Jim Tressel

Started in: 2001

Winning Percentage: .817

School's Winning Percentage Since 1960 Excluding Current Coach: .752

School's Winning Percentage In 25 Years Before Current Coach: .730

School's Winning Percentage In 10 Years Before Current Coach: .756

Tradifference: +.071

Tressel has done the near impossible: come to a school with an incredibly high standard of success and exceed expectations.  Now if only he had won all those BCS games...

Schoool: Wisconsin

Coach: Bret Bielema

Started in: 2006

Winning Percentage: .731

School's Winning Percentage Since 1960 Excluding Current Coach: .487

School's Winning Percentage In 25 Years Before Current Coach: .545

School's Winning Percentage In 10 Years Before Current Coach: .709

Tradifference: +.151

Much like Ferentz, Bielema had the unenviable task of succeeding the most successful coach in program history.  If not for Barry Alvarez, Bielema's score would be even higher.  He has continued Alvarez's success transforming Wisconsin into a consistent power, though he hasn't managed to break through for a conference title yet.  

Schoool: Northwestern

Coach: Pat Fitzgerald

Started in: 2006

Winning Percentage: .540

School's Winning Percentage Since 1960 Excluding Current Coach: .329

School's Winning Percentage In 25 Years Before Current Coach: .342

School's Winning Percentage In 10 Years Before Current Coach: .420

Tradifference: +.176

As previously disclosed on this site, Fitzgerald is in fact a wizard.