Andrew,
the conclusion is that teams are largely comparable in their ability to evaluate, with luck being the biggest factor in year-to-year success.
I don't believe that for a second, and a lot of raw data bear that out. There is a reason why Oakland has been bad for a long time, and for years it was Al Davis taking players who were not very good. There is a reason why the Browns have been bad. A lot of their draft picks have just sucked. It's looking at teams whose draft picks are out of the league sooner than others. Trent Baalke is a better evaluator than TD was. There is reason why the Steelers have gotten great rush LBs year after year after year--and in all rounds. They know how to evaluate that position. To get a sense of how well Baalke did, take a look at the kinds of trades other teams were making:

Trading up:
To get the 18th pick we gave up the 31st and 74th. (13 spots)
Atlanta, to get the 22nd, gave up the 30th, 92nd, and 198th (they did get a 7th rounder next year, also) (8 spots)
St. Louis, to get the 8th pick, gave up the 16th, 46, 78 and 222. St. L. also got the 72. (8 spots)

To get the 55th, we gave up the 61st and 173rd (5 spots)
Trading back:
To get the 34th, Tenn. gave us the 40th, 216, and a 3rd rounder next year. (6 spots)

Baalke is just schooling people in trades. And I just can't agree that standing pat to keep a 7th rounder is better than using it to move up to get a player you may not get otherwise. I am not big on trading up, and am dead set against it when you start talking about 3 or more picks inside the 3rd round, but Baalke didn't do that at all. The pundits were speculating that to move up to the mid-1st the 9ers would have to give up the 31st, 34th, a 3rd rounder, and a late rounder. We got it for a 3rd rounder period.