Unlike their impact on some of the NFL's perennial contenders, compensatory draft picks haven't done much to compensate the Vikings since the concept and mysterious distribution formula were born 20 years ago.

For starters, the Vikings haven't had a compensatory pick higher than the fourth round.

Secondly, they have had only 16 total. The Ravens, who didn't even exist the first two years of compensating picks, have had an NFL-high 41. That's eight more than runners-up Dallas and Green Bay.

Thirdly, three of the Vikings' four highest compensatory picks became Shawn Worthen, Cedric James and Ed Ta'amu.

Who?

Exactly.

Worthen and James, teammates at Texas Christian, were back-to-back picks (130-131) in 2001. They lasted a combined nine games over one season. James, a receiver, was taken 103 spots higher than Cincinnati's T.J. Houshmandzadeh.

A year later, Ta'amu, a guard from Utah, was taken 132nd overall. After being cut in training camp, he was out of football for three years before starting a lengthy Arena Football League career.

According to the NFL, compensatory picks are determined by a formula based on salary, playing time and postseason honors. Teams losing more and/or better free agents to other teams than they acquire are compensated.

"I don't know how the formula works, to be honest with you," said Jon Gruden, ESPN analyst and former Super Bowl-winning coach. "But we never went into free agency saying, 'Let's let Bobby and Billy go so we can get a compensatory pick to replace him.' "

Although the formula isn't public knowledge, it's obvious some teams understand it well and use it to their advantage. Exhibit A: the Ravens with General Manager Ozzie Newsome.

Seven months ago, the Ravens had four picks, including three in the top four rounds. They had traded their seventh-rounder for Colts center A.Q. Shipley and their fourth- and fifth-rounders for Jaguars left tackle Eugene Monroe.

Today, through the magic and mystery of compensatory picks, the Ravens have doubled their picks to eight and their number of picks in the top four rounds to six.

Yes, 15 months after winning their second Super Bowl, the Ravens received the maximum number of four compensatory picks. They got an extra pick in the third round (No. 99), two in the fourth (Nos. 134 and 138) and one in the fifth (No. 175).

The formula was based on last offseason, when the Ravens lost four key members of their Super Bowl champion team — Paul Kruger, Ed Reed, Cary Williams and Dannell Ellerbe — to free agency while signing nobody noteworthy.

In many cases, Newsome gets more in compensatory consideration for used veterans that cost him considerably less to acquire when they were new. Ellerbe, for example, was signed as a rookie free agent, while Williams arrived via Tennessee's practice squad.

"Our approach is we come to a threshold of what we think the player's [maximum] value is in Baltimore," Newsome said years ago at the NFL combine. "When it goes beyond that, then we don't mind them going out the door."

Compensatory picks can't be traded. But the expectation of four compensatory picks this year is what allowed Newsome to trade his own picks for two starters, Shipley and Monroe, the eighth overall pick in 2009.

Three of Newsome's compensatory picks have gone on to make at least one Pro Bowl. And that doesn't include running back Chester Taylor, a sixth-round pick who became a 1,200-yard rusher with the Vikings.

Overall, it's been a good 20-year run for compensatory picks. At least outside of Minnesota, where the leader in the clubhouse remains defensive tackle Jason Fisk, a 1995 seventh-rounder who played four seasons (5½ sacks) for the Vikings and 12 years overall.

Cowboys Hall of Fame guard Larry Allen (second round, 1994) was among the first compensatory picks. And he's not even at the top of a list that includes Hines Ward, Brian Dawkins and Mike Vrabel.

No, that spot has been occupied for some time by a man named Tom Brady, who was quite the sixth-round bonus pick 14 years ago.

Mark Craig • mcraig@startribune.com