Here's a big waste of time I decided to work on:
I've compiled a list of every DT (4-3 DTs, 3-4 NTs, and 3-4 DEs) that has played in the past 5 years. Using PFF ratings for each one, I have done a couple things:
Charted average rating with years played:
As you can see, DTs have a small bump in skill in year 2, but don't really seem to have a large change until year 7. After 11 years, they are typically done. I don't know what happens in year 9.
Charted number of players in the league with years played:
The vast majority of DTs are in their first 4 years. This is totaled over 5 years, so to get the average number of players per year, divide by 5.
Charted total rating over the past 5 years with draft position (the clump at the end is UDFAs):
This looks like a bunch of nonsense. I'm hoping that comparing this with other positions (and maybe with some smoothing) will yield some meaningful results.
Cool note: The biggest bust by far is Tyson Jackson. His -43.8 is the 3rd lowest rating of all 395 players that have played in the last 5 years. The 2 guys worse than him were drafted 81st (Roy Miller, -47.1) and 152nd (Antonio Johnson, -46.8). Jackson, as you know, was drafted 3rd.
The best value? No one has been as good as Justin Smith (+169). He was drafted 4th, though. Geno Atkins wasn't drafted until the 120th pick, and has a rating of +125.4.
Anyway, I'm planning on doing all positions, I decided to do DTs first, what with Star coming out and all. I'll post the other positions here as well if people are interested. If not, I'll keep it all to myself.