To the OP - well thought out post, but if I were the Broncos FO I would strongly disagree.
1. Don't move a young first team pro-bowler to a new position. Just don't, ever. The position (in JDR's defense) is just perfect for him. Perfect player in the perfect position with the perfect coach. Just don't get too fancy here and we will have something historically special.
2. We had the money to keep Dumervil. Repeat that, we had the money to keep him, yet we let him walk to another AFC team (the team that ruined our SB hopes). Ask yourself why? Because the coaching staff thinks they can replace his cumulative production. Every move Elway has made has been to make us better - now. We have to trust his decision to change our defense.
3. Freeney is still on the shelf, losing money as we speak. Chances are that he doesn't even sign with a team until training camp. And, don't expect that he will actually get anywhere near the $6 mil he was asking for. I think that once his true value sets in, we still have a 50/50 chance of signing him as a situational pass rusher.
4. Remember that we picked up Elvis in the fourth round. Don't push so hard for a first round DE that you pick a project that might not pan out (remember our old friend Jarvis Moss?). First rounders need to be Game 1 starters, and i'm not sure that many of the DE's available at #28 will beat out the guys already on the roster.
5. With a larger DT combo this year, it makes it much easier to bring pass rush from the interior. Not from the DT's themselves, but from ILB blitzes. I would much rather pick up the best blitzing ILB available (which fills another significant need), than take a chance on an injured, old, or project DE.
Who knows, you could be absolutely right, but my two cents says otherwise.