Continued: Henderson's brother leads group of 16 free agents

Erin Henderson was confident enough in his draft stock that the Maryland linebacker declared for the NFL draft a year early. It appeared to be a safe move.

Henderson, whose brother E.J. is the Vikings' middle linebacker, was projected as a possible second- or third-round pick.

But after the seven-round, two-day draft concluded Sunday, Erin Henderson and the Vikings agreed to terms on a rookie free-agent deal. Somehow, he made it through 252 picks without being selected.

Henderson was one of 16 undrafted free agents with whom the Vikings agreed to terms. He suffered two knee injuries in college and missed the 2005 season because of a torn left anterior cruciate ligament. The New York-based agents who represent Henderson declined comment.

The Vikings also agreed to terms with quarterback Kyle Wright of Miami (Fla.); cornerbacks Brandon Sumrall of Southern Mississippi and Marcus Walker of Oklahoma; safeties Travis Key of Michigan State, Husain Abdullah of Washington State and Marcus Griffin of Texas; defensive end Martail Burnett of Utah; defensive tackle Leger Douzable of Central Florida; kicker Steven Hauschka of North Carolina State; receivers Nate Jones of Texas and Darius Reynaud of West Virginia; linebacker J Leman of Illinois; center Tim Mattran of Stanford and tackle Drew Radovich of Southern California; and running back Albert Young of Iowa. Mattran is from Chanhassen and went to Chaska High School.

The Vikings will start a three-day rookie minicamp Friday.

The Vikings center is sitting out the voluntary portion of the offseason program and his contract expires after the season. On Sunday, the Vikings drafted a big-school center.

Are the two items related?

"Really, it doesn't have anything to do with Matt Birk at all," coach Brad Childress said of the decision to draft Notre Dame center John Sullivan in the sixth round. Childress said Sullivan was "the only offensive lineman that we had right in there at that level."

Notre Dame coach Charlie Weis gave Sullivan a strong recommendation. Sullivan was considered a top prospect as a junior, but evaluations dropped after a down year.

"The 2007 season at Notre Dame was a struggle," Sullivan said, "but at the same time, I like to look at it as a learning experience."

Last season, the Vikings' two backups at center started at other positions: right tackle Ryan Cook and right guard Anthony Herrera.

The Vikings were unable to secure depth at tackle through the draft. Childress said the Vikings have retained all of their depth from last season.

At issue is who would play left tackle in the event that left tackle Bryant McKinnie is suspended by the NFL. "I'm OK with [the situation]," Childress said. "We have Chase Johnson, [who] I believe will be a year better. You have Artis Hicks, who has that swing capacity there, and Marcus Johnson. So none of that has changed. Nobody has left us in that regard there."

In order to secure fifth-round pick John David Booty, the Vikings and Packers, of all teams, swapped fifth-round picks in exchange for the Vikings' seventh-rounder (No. 209).

The agreement enabled the Vikings to move up 13 spots in the fifth round. According to Vikings VP of player personnel Rick Spielman, exchanging draft picks is much different than trading a player.

"The picks are your currency," Spielman said. "So it's not as big a factor, especially if we covet something that they don't covet, and they may want to accumulate more picks. That's more to me just exchanging currency. Now, if it's a player involved, that might be a whole different ballgame."