now that i have some time to go into detail.
yes, coaching is a big deal. but, you will usually find (and i can give several examples) that when a particular unit is terrible, it isn't just the coaching.
take florida's offense. florida's offense has been very well coached this season and they still are far from a powerful offensive unit. the staff has used everyone's gifts to their best potential and has used some creativity to gain production. but, at the end of the day, even with quality coaching and improved play.....it's a mediocre offense.
same holds true for the 2009 vol offense. yeah, it was better than the 2008 clawfense. a lot of improvement was made. but, it wasn't a very good offense either.
florida state fans thought when they get rid of jeff bowden, their offense would take off. it didn't.
when a unit is poor, as in ranking in the 100's poor.....a coaching change or a year of development can help. but, odds are there is also a talent problem and i believe it exists at every level of tennessee's defense.
as for 2011 vs. 2012....., the stats in 2011 are deceiving. as i joked at one time, the tennessee defense is the only defense that ever made john brantley look good. they gave up big plays throughout 2011. it just pales in comparison to 2012. lord knows, it has been years since tennessee was able to harrass an opposing qb. and if you are thinking, yeah, but not against akron and troy.....montana scored on an 80 yard td pass.
in addition, offenses throughout the league improved.