Re: 3-4 to a 4-3?
Always thought about a switch to a 4-3 but there are some credibility issues with how it is laid out in the article.
For one Jason Worilds was a DE in college and would play there in a 4-3 defense. In no way is he up for the almost constant pass coverage required of a 4-3 OLB.
Timmons however did in fact play ouside in a 4-3 and would be a perfect fit there.
Woodley also would fit perfectly in a 4-3 and would excell more there pass rushing all the time. We would still need a probable upgrade at the other DE unless Worilds could excell there too.
Heyward did not play end in a 4-3 at Ohio State but a 3-4 most of the time. He would not be what you want in a 4-3 end. (Think Dwight Freeney, Robert Mathis etc.) So that leaves Heyward, Hood, McClendon, Ta'amu, on the inside with Hood being the best of the lot.
Spence I thought was a OLB at Miami then maybe moved inside. It is very debatable his ability to be the man in a 4-3 defense and the inside linebacker does need to be the man. So a likely draft upgrade there would likely be needed.
So a good 4-3 end, a tall lanky coverage OLB, and a really good ILB really is what is currently preventing this team from switching to a 4-3. I personally would like to see a hybrid where both can be played week to week and even in game if possible. The Steelers do a little of that now and the Patriots did a lot of it when they were cheating (I mean winning) Super Bowls.
Also teams playing 4-3 must really stockpile those Defensive Lineman and be two deep accross the board meaning less linebackers and less viable special team players to make tackles. The trouble is if Woodley is injured say for the year there really is no viable replacement for him on the roster. Free agent signings and lots of drafting would be needed to create that depth.
However being a number one defense last year may make the old adage "If it ain't broke don't fix it" the Steelers way of thinking.