After reconstructing the roster in the offseason, then spending the past five months evaluating it, Vikings coach Mike Zimmer and General Manager Rick Spielman have picked their 53 men.

Sure, those 53 men will change, perhaps even before Sunday's season opener in St. Louis. Heck, it might already have changed since this reporter clicked the send button. But if one thing stands out while skimming the roster, it's the relative youth of these Vikings.

Spielman has gradually turned over the roster since the team's run to the NFC Championship Game in 2009, shaving years off the average age of his players in the process.

He and Zimmer took it another step further this offseason, which included Saturday's release of a pair of 30-somethings in Chris Crocker and Fred Evans. Jamarca Sanford, a 29-year-old, was in danger of being cut, too, but ended up on injured reserve.

The Vikings now have more rookies (nine) than players aged 30 or older (eight), and 60 percent of their roster — 32 players of 53 — is younger than 26.

This time a year ago, the Vikings were near the middle of the pack with an average age of 26.0, according to research by Philly.com. Now it is 25.6, which will make them one of the youngest teams in the NFL. That doesn't necessarily have to be a bad thing, though. After all, the Seattle Seahawks, last year's Super Bowl champions, had an average age of 26.4 in 2013.

And while promising draft picks such as quarterback Teddy Bridgewater, running back Jerick McKinnon and defensive end Scott Crichton will start their careers backing up established veterans, not all of the team's youngsters are patiently waiting in the wings.

The Vikings are expected to start 10 players aged 25 or younger, including outside linebacker Anthony Barr, their top pick in May's draft. Kicker Blair Walsh and punter Jeff Locke also are younger than 26, as are several other players who will be asked to take on meaningful reserve roles.

But even today, with the original 53-man roster unveiled and the season opener against the Rams only six days away, a few important personnel decisions remain. While last week Zimmer made the big one, choosing veteran Matt Cassel as his quarterback over the first-rounder in Bridgewater, he still has yet to name the starters at middle linebacker and the second of his two safety spots.

Jasper Brinkley appears to have the edge over Audie Cole at middle linebacker. He is the more experienced of the two, and his downhill style fits what Zimmer is looking for on early downs. And while Brinkley isn't the most trustworthy player in coverage, Cole is not head and shoulders above him in that regard. Regardless of who starts, the "Mike'' will play only about 40 percent of the snaps.

Crocker seemed to be Zimmer's choice to start next to fellow safety Harrison Smith. He had spent the past seven years with Zimmer and came out of virtual retirement to join the Vikings when the injury bug feasted on the hamstrings of their defensive backs. But with his release, along with that of veteran safety Kurt Coleman, it looks as if 24-year-old Robert Blanton is probably going to line up as the other safety.

As for the third cornerback, which is essentially a starting position in today's pass-happy NFL, Josh Robinson looks like the most likely candidate, though Zimmer likes Shaun Prater and Jabari Price.

Beyond that, there is not much left for us to try to figure out before the officials roll out the footballs for the Vikings and Rams on Sunday. But with a bunch of intriguing prospects and nine new starters, including seven on defense, there still will be plenty of intrigue as the Zimmer era gets underway.

Matt Vensel • matt.vensel@startribune.com