Buddy Ryan left the Vikings as defensive line coach to become Bears defensive coordinator in 1978. By 1985, he had reached the peak of his football genius as the father of the famed "46 defense," a brilliant scheme that overloaded the line of scrimmage with players who stuffed the run on their way to terrorizing the quarterback.

That season, the Bears led the league in scoring defense (12.4 points allowed per game), shut out the Giants (21-0) and Rams (24-0) in the NFC playoffs and then whipped New England 46-10 in Super Bowl XX.

In 1995, that same scheme was in place when Ryan was the head coach in Arizona. The Cardinals ranked last in scoring defense (26.4), finished 4-12 and got Buddy fired after only two seasons in the desert.

This came to mind on Monday while watching Vikings coach Leslie Frazier describe another loss in a 1-6 season. Twenty-eight years ago, Frazier was a bump-and-run cornerback who was vital to the success of Ryan's scheme. Monday, Frazier was tiptoeing the line between protective coach who doesn't want to bad-mouth young players and team visionary trying to salvage a season that's coming up short on personnel.

The Vikings' third-down defense — or utter lack thereof — was the open wound du jour. The salt being rubbed in by reporters came via Sunday's 72 percent (13 of 18) rate of third-down failure vs. Aaron Rodgers and the Packers.

Admitting there isn't much that can be done about personnel in late October, Frazier talked about how the coaching staff will spend this week looking for ways to improve the scheme. After he left the lectern, Frazier was stopped for a quick general discussion about the relative value of coaching schemes vs. personnel in the NFL.

"Give me the personnel any day," Frazier said. "All great teams, it's the personnel. Even when a coach makes a bad call, if you got the right personnel, they make it right."

The Vikings have used essentially the same 4-3, Cover 2-based defense since 2006. Rodgers had faced it 10 times in the regular season before Sunday, and his 116.4 passer rating ranked No. 1 in the league since 1970. He then went out and improved on that number, posting a 130.6 rating while completing 12 of 12 passes for 187 yards, eight first downs and two touchdowns on third and fourth downs.

"For the most part, our defense is pretty much what Aaron saw in 2008," Frazier said. "We've done some things from year to year against him to add some wrinkles. We also play far less Cover 2 [two deep safeties] than we did in 2008. I don't know if that's good or bad, based on what just happened."

Frazier said he and the coaches aren't looking at wholesale scheme changes this week.

"I'm not doubting the scheme," he said.

Frazier doesn't have the personnel to make grand changes schematically even if he wanted to. Starting free safety Harrison Smith is on injured reserve. Starting strong safety Jamarca Sanford (groin) and starting right cornerback Chris Cook (hip) aren't looking good to play Sunday. And the other top-three corners, Josh Robinson and Xavier Rhodes, are green and greener, respectively.

Frazier also was asked whether the Vikings have become too predictable on defense while so many successful franchises such as the Packers employ exotic 3-4 schemes that constantly move players around and use multiple fronts to confuse quarterbacks.

"Well, in some cases we are getting predictable," he said. "But in other cases, I think we need to execute a little bit better. Part of that is guys learning what we're asking them to do. The lack of experience sometimes shows up. We have some things like three down [linemen] in our package, but we haven't used it as much."

Again, it comes down to personnel. In 2011, Frazier didn't have Smith and was without his starting corners for a combined 21 games. The secondary had no depth and was historically awful.

In 2012, General Manager Rick Spielman traded back into the first round and grabbed Smith, who was an instant success. Coupled with Antoine Winfield, who was at his savvy best in the slot corner spot, the Vikings exceeded expectations.

In 2013, the gamble was made to release Winfield in favor of Robinson's potential. And now Smith is looking at the probability of missing the final 11 games.

When judging a coaching staff, it's always worth remembering personnel details such as these. Buddy Ryan, after all, was a much better coach when he had Mike Singletary, Dan Hampton, Richard Dent, Otis Wilson, Wilber Marshall, Dave Duerson, Gary Fencik, Leslie Frazier and so on.

Mark Craig • mark.craig@startribune.com