Late in Leslie Frazier's dead-coach-walking 2013 season, an overserved Metrodome patron wobbled to the front of press row and began editorializing on the overall competence of Frazier's offensive coordinator, Bill Musgrave.

"Musgrave!" the man screamed the way one does when he's hovering at .20 or higher. "You …"

The next word sounded like "duck" but wasn't.

The man kept repeating this opinion in the direction of the coaches booth. The Vikings lost and everyone went home to sleep it off.

Three years later, that fan probably views Norv Turner's unforced resignation on Wednesday as some form of joyous magic elixir for a 5-2 team that's reeling but still sitting atop the NFC North against all odds offensively. We'll see if interim coordinator Pat Shurmur will be able to sprinkle some of this imaginary potion over an Adrian Peterson-starved running game and a tackle trio that includes two young, scrappy backups and a 31-year-old veteran trying to come back from major knee injuries midseason with a new team after having played 11 snaps all last season.

As for Muskie? Well, in case ya missed it, he's the offensive coordinator of the Raiders team that just tagged the Buccaneers with 626 yards of offense, 513 of them passing, and a 30-24 loss in Tampa. The Raiders (6-2) committed an NFL-record 23 penalties for 200 yards and still put up 356 yards more than Tampa Bay.

In the NFL, yesterday's goat tends to be today's guru, and vice versa. Once upon a time, even Bill Belichick was a dumbbell. Or so people thought.

So the Vikings head into Sunday's game against the visiting Lions oddly unstable in the coaching ranks for a division leader at the midway point of a season.

Norv haters will take me to the Twitter stoning station for this one, but this time a year ago, Norval headed to Detroit with Teddy Bridgewater and Adrian Peterson healthy. Teddy threw for 316 yards, Adrian ran for 98, Mike Zimmer's defense beat up Matthew Stafford, and everyone returned home with a 4-2 record and smiles on their faces.

A day later, it was the Lions, at 1-6, who were in flux. Hours after coach Jim Caldwell said there would be no major changes to his staff, he either changed his mind or had his arm twisted from above.

Caldwell fired offensive coordinator Joe Lombardi and line coaches Jeremiah Washburn and Terry Heffernan. Quarterbacks coach Jim Bob Cooter, who was 31 at the time, was promoted.

Lombardi is the grandson of Vince. Yeah, that Vince. But if ever a change was necessary, it was that one.

In a Week 2 road loss to the Vikings, Stafford was hit so hard so many times that he had to have his ribs X-rayed after the game. Four games later, in the rematch, it was his left hand that needed X-rays after the Vikings sacked him seven times and hit him an additional 13 times. And many of those hits and sacks came from completely unblocked defenders.

Since then, the Lions are 10-7, including 4-4 this season. Stafford has compensated for the retirement of receiver Calvin Johnson with an impressive combination of system comfort, extreme arm strength and one heck of a fast-moving brain. His top five targets have 38, 36, 34, 33 and 25 catches, and include three receivers, a tight end and a running back.

"Some of the things they run are similar, but there's also some different concepts they do [under Cooter]," Zimmer said. "But, really, the biggest thing to me is Stafford is playing at a really high level."

Since Cooter and Stafford teamed up the day after the last Vikings meeting, Stafford ranks third in the league in passing touchdowns (36), third in completion percentage (68.4) and fifth in passer rating (104.3).

"I think Matthew's done a good job of telling me plays he likes or plays he doesn't like," Cooter told reporters recently. "So it's his offense as much as it is mine, maybe even more."

Mark Craig is an NFL and Vikings writer. Twitter: @MarkCraigNFL E-mail: mcraig@startribune.com