Very Interesting Points - On a Jets board there's a big debate about the similarities between this and Vilma with regards to the switch to the 3-4.....
Was it the 3-4 and lack of "protection" that hurt Lewis or is it more of just a natural decline do to age? Probably a combo, which is more? Would a younger Ray Lewis have thrived no matter what?
The thing to remember is that Baltimore didn't run a very typical 3-4.In the typical 3-4, your defensive lineman usually play 2-gap schemes, just trying to tie up blockers to keep the LBs clean. As a result, it's easier for offenses to get blockers onto SPECIFIC LBs (although hard to since there's an extra LB, there are theoretically just as many LBs free on any given play).
The Ravens played more of a 1-gap 3-4 defense, unique in the league as far as I know. Their DL was geared more towards penetration rather than occupying blockers. They had Edgerrton Hartwell at ILB playing like a second SLB, and Ray Lewis playing like a SS.
If you're familiar with IDP leagues, you will probably know that SSs tend to get a ton of tackles, and SLBs tend to get relatively few. This is because the SLB's job is to tie up blockers to leave the SS free to come up and make the play. That was how Hartwell played- he tied up blockers, leaving Lewis free to make the play. As a result, while most LBs lose protection when they go from a 4-3 to a 3-4, Baltimore didn't employ a standard 3-4, so Ray Lewis wound up with just as much protection. In fact, while I don't know the exact reason for the switch, I speculate it's because Lewis was declining and they needed to take new measures to keep blockers off of him or watch him become mortal again.
As a result, Lewis played pretty well still until this last season. You'll notice he wasn't demanding his front office get some players to keep blockers off of him, at any rate. Anyway, last year was the first time since the 2001 that the Ravens didn't run a scheme directly designed to keep Lewis clean... and you saw what the result was. Lewis whining on draft day until Baltimore took a DT.
How will this affect Vilma? Well, I expect his production to drop in a 3-4. Lewis's didn't, but Baltimore ran a very unique 3-4 designed to funnel all plays towards Lewis still. I somehow doubt the Jets will be running a similar scheme.