The renown and well-respected website Pro Football Focus is in the process of grading the 2008-10 drafts of each of the 32 NFL teams, and have just released their analysis of the Vikings.
The drafting of Percy Harvin 22nd overall in 2009 and John Sullivan (a favorite of PFF), a sixth-round selection in 2008, received the highest grade of any draft pick by the Vikings during those years, each earning a +1 rating on a grading scale between +2 and -2. As noted in the preamble, PPF analyzed each draft choice on a criterion consisting of four different categories: what round they were drafted in, level of performance, contribution, i.e., the percentage of snaps they played, and "other factors such as unforeseen injuries and conditions that could not have been accounted for," the latter of which might be considered rather ambiguous and discretionary.
No Vikings were the recipient of either the highest or lowest rating -- though, it is somewhat dubious how Tyrell Johnson (an absolute bust that the Vikings traded up in the second-round of the 2008 draft in order to select) earned a rating of -5 only, the fourth-worst grade.
PFF's conclusion, though, that the Vikings are a team that "...haven’t really hit on their late-round picks, and ... by and large they’ve just found guys who can fill a roster spot without pushing on and improving the team," is an analysis that most fans would probably agree with.