Posted by ESPN.com's Kevin Seifert
As we compile our notes in Detroit for a Lions-dominated mailbag later this week, it made sense to explore a topical and interesting Minnesota Vikings question.
Erik of Oregon writes: Why don't the Vikings just move Sharper back to free safety and play Boulware or Johnson at SS where they are more suited to play? Sharper was a FS his entire career until he was paired with Dwight Smith, why not just move him back?
Kevin Seifert: Technically, Darren Sharper has been playing strong safety since the Vikings installed the "Tampa-2" scheme in 2006. As counterintuitive as it sounds, the differences between free and strong in this scheme aren't that dramatic.
Intuitively, we all consider the "strong" safety to be a hard hitter -- the guy who plays close to the line, supports the run and takes on tight ends. It also stands to reason that the "free safety" is the center fielder -- the last line of defense against the run and the guy who is allowed to break on the ball when it's in the air.
Sharper has played in defenses like that in the past, but in the Tampa-2 (really, all cover-2 defenses) the safeties essentially split the field in half. One has responsibility for one side, and one for the other.
Coaches will tell you the two positions are interchangeable, but I think that's usually to mask the subtleties of the scheme. There are some differences. But all of this is a very long-winded way of saying it wouldn't change much if the Vikings moved Sharper to free safety and put Tyrell Johnson or Michael Boulware at strong safety.
On a related note, Johnson returned to practice today in Minnesota after sitting out two days with a strained abdomen. Madieu Williams is expected to miss a total of about six weeks but, according to the Star Tribune, he escaped what some doctors thought might be a career-threatening injury to his neck.