The NFL draft has come and gone, but that doesn’t mean we are at the end of the constant chatter or speculation.

If only we were that lucky.

Instead, we have entered that period of time when everyone must rush to declare winners and losers and immediately declare how each team fared with its picks.

How can anyone really know? Well, they can’t — and that’s the beauty of the instant draft “grade.” Mel Kiper Jr. of ESPN has already declared this Vikings draft to be a B-minus.

If only Rick Spielman had studied harder and applied himself a little more.

Far more instructive is looking back at past drafts and past grades to see how things that were immediately declared actually played out.

We’re not picking on Kiper here, because he does a good job, but we did go back and look at how he graded Vikings drafts from 2006-2011, years in which we now have a pretty good idea of how things turned out. Here are some highlights:

2006: Kiper called Chad Greenway a “very good pick” at No. 17 overall, which has proven true. But he also said Tarvaris Jackson “has a chance to be Vikings’ future quarterback. His grade: C+. Our grade of his grade: B-.

2007: Adrian Peterson was called a “potential franchise running back.” You think? Sidney Rice in the second round was a “great value pick,” which was accurate. But Kiper also said, “Aundrae Allison spent time on the Big Board in 2006 and was a good pick in the fifth round; Rufus Alexander was a solid sixth-round pick.” They didn’t quite pan out. Kiper’s grade: B+. Our grade of his grade: B.

2008: This might be Kiper’s biggest miss. He wrote, “I had safety Tyrell Johnson going in the first round, so to get him in Round 2 (43rd overall) is a great pick because Johnson has big-time skills.” He also praised the pick of QB John David Booty in the fifth round. Neither really worked out. Kiper’s grade: B. Our grade of his grade: C-.

2009: He said the Percy Harvin pick “could end up being a good selection,” but he was skeptical because of character issues. He also praised third-round pick Asher Allen. Kiper’s grade: C+. Our grade of his grade: B-.

2010: Kiper was down on this draft, questioning the picks of Chris Cook and Toby Gerhart while calling Everson Griffen “inconsistent.” He was spot-on with Cook, to be sure. Kiper’s grade: C-. Our grade of Kiper’s grade: B.

2011: Kiper said the Vikings reached for Christian Ponder at No. 12 and got good value with Kyle Rudolph in the second round. He pretty much nailed it. Kiper’s grade: C+. Our grade of Kiper’s grade: A-.