I'm going to respond, and then go on a semi-rant not at all aimed at you.
If drafting was the only way to stock a team, than evaluating just the draft would make a good deal of sense. However, BB has made extensive use of signing FA's, UDFA's, and making trades.
I've seen articles claiming that the 2007 draft was a bust, but they do not consider the trades to obtain Moss and Welker, adding their value to that draft makes it anything but a failure.
Most if not all Coaches around the NFL are on much less firm ground than BB is here. Therefore many of these Coaches will hold picks on the roster for years - well after the time it's clear that they can't help, to avoid the negative PR of cutting them. BB's cutting of medium/high picks has to be right at the top of the league. All BB cares is that if someone on the 90 man is better than someone else, than he'll keep the better player.
I've seen articles the past 3 years that I don't have the URL's for that say BB is the best GM since he started with the Pats when everything is considered.
Another factor is that BB the trader has often added to his haul of picks - say from 6 to 9, with one forward into the next year. Those that want to burn BB will say - see? After 3 years he only has two guys left from 11 picks. Well, the amount of room available on a team's roster with 17-2 or a 14-4 record is limited, and if they don't count the 3 UDFA's and 3 FA's that were brought in as well - not to mention not spending money on older players that BB has walked away from (his record here is almost impossibly great).
Do I wish more of his 2nd rounders were still here and playing at a high leve - sure - but - careful of the agenda/carelessness of those that claim BB is anything other than stellar as a GM overall.