As if you needed any reminder why it was so important for the Vikings to identify, target and acquire another attempt at a QB of the future, recent QB rankings assembled by ESPN.com's Mike Sando provide an imperfect but telling look around the NFL.

The methodology, per Sando:

I asked 26 league insiders to grade every projected starting quarterback on a 1-5 scale, with "one" reserved for the best and "five" for the worst. Eight general managers, two former GMs, four pro personnel evaluators, seven coordinators, two head coaches, two position coaches and a top executive participated, attacking the project with gusto almost across the board.

That's a pretty good sampling, and while the 1-5 scale is far from perfect, with 26 people voting the number probably winds up being pretty close to what it should be.

Five QBs wound up in Tier 1: Tom Brady, Peyton Manning, Aaron Rodgers, Drew Brees and Andrew Luck. Three of those five are with the teams that drafted them. Manning played forever for the Colts before a late switch to Denver. Brees is the anomaly, having taken a little while to find his groove before settling in with New Orleans.

All 10 QBs in Tier 2 have played with one team for their entire careers: Philip Rivers, Ben Roethlisberger, Matt Ryan, Tony Romo, Russell Wilson, Eli Manning, Joe Flacco, Matthew Stafford, Colin Kaepernick and Nick Foles.

In Tier 3, it's a mixed bag of two-team QBs, journeymen and young QBs trying to find their way.

And in Tier 4, we find that same mixed bag, even more so — including the No. 28 QB on the board, the Vikings' Matt Cassel.

The Vikings tried to draft and develop a QB in 2011 with Christian Ponder. That clearly hasn't worked out or Cassel wouldn't be here. And even if Cassel represents an upgrade over Ponder, this is still what was written about him by Sando after the query with those 26 football experts:

Cassel was at his best in New England and Kansas City under Charlie Weis. There's some thought among evaluators that he has a tendency to hold the ball and stare down his receivers in the absence of proactive coaching. Perhaps Norv Turner can help him out. "Everything has to be right to win games with him," a GM said.

Indeed, it will be interesting to see if Turner can push Cassel more toward the middle of the pack than the lowest tier. But that's probably the ceiling, and a good reminder that taking another shot at a franchise QB with Teddy Bridgewater needed to happen.