It was more so switching to a 4-3 defense that got us over the hump, imho.
That is very much an overly simplistic way of looking at it. Absolutely the defense improved, but it wasn't simply due to a difference in scheme, it was due to a fundamental change in philosophy, from strength sacrificing speed to speed adding strength. We changed everything about that defense from the ground up.
In the seven straight bowl games we lost from 1988-1994 we gave up an average of thirty points a game, then dropped that to just 20 points a game in the ensuing four straight wins. That's a pretty big change.
But it wasn't just the defense that changed, getting us over the hump - the offense in that time went from pedestrian to high-octane, as evidenced by those same bowl game results. In the seven losses from 88-94 we averaged 22 points per game. In the ensuing four straight wins we averaged 42 points a game. That offensive leap blows anything we did on defense out of the water.
So absolutely the defense's changes contributed to our improved performance, but by no means was it the only change, and stats show it may not have even been the biggest change.
That offensive leap was largely credited to the defensive leap, according to Osborne. He said it was easy to put up that many points because the offense was constantly starting in great field position. It is a team sport afterall.
When Osborne talked about the switch to the 4-3, he gave as much credit to the dime package as the base switch. He also, in the same breath, described fundamental changes to the recruiting philosophy, focusing on speed. You cannot find a quote where Osborne attributed our 90s success to a switch to the 4-3 defense alone, nor do I believe there is a quote out there supporting the notion that our offensive success came from the switch to the 4-3.
What you will find is Osborne saying things like:
"Once we got the dime package and found we could stop the run with that defense as well, we went to the 4-3 defense in 1992. We recruited people who could cover man-to-man, went to smaller, quicker defensive people up front and made the switch away from the 5-2 defense for the first time in almost 30 years. When you can pressure on defense, get the ball back to your offense, you can do a lot of things with the offense. "
Dr. Tom was not
solely crediting the 4-3 switch with our success as you seem to be implying (and if that's not what you're implying, forgive my misunderstanding). It was a combination of things, including recruiting speed and better coverage people. All kinds of things.
My point is that, no matter how good our defense is, without a good offense we're never going to improve. Nothing earth-shattering about that. And the basis for your offense is your offensive line - again, not breaking any new ground with this thought.