Comparing last year's defense to this year's is apples and oranges.
Last year, with Bray out, Vols' offense was pathetic, really pathetic. Get a couple of scores up on them and the game was over. Like Fulmer did so many times against inferior SEC teams, folks like LSU and Alabama got ahead, sat on the ball and basically ran the clock out so as not to embarrass further the opposition. Concurrently, with UT's offense so anemic, it didn't matter that the defense played "bend but don't break" and stayed on the field forever giving up drive after drive with no chance of a turnover or big play on defense.
That's why Dooley really didn't care that Wilcox left. Dooley wanted a big play defense so that his big play offense would get plenty of opportunites. Get some 3 and outs on defense, force a turnover at the expense of giving up more big plays. But get UT's offense on the field. Obviously getting one big play for every 10 you give up ain't gonna work, but that was the idea.
Wilcox's defensive philosohy doesn't fit with a high powered, up tempo offense.