Vikings cornerback Xavier Rhodes’ film study changed this week when preparing for a Lions team without star receiver Calvin Johnson, who retired this offseason.

“When they had Calvin, you knew it was just that one guy,” Rhodes said of Detroit’s offense. “Now they’re spreading the ball around, throwing to everyone.”

And somehow, Lions quarterback Matthew Stafford has excelled without his No. 1 target. Stafford is on pace to set a handful of career bests halfway through the season, including completion percentage. Stafford’s 103.4 passer rating trails only Tom Brady, Matt Ryan and Drew Brees.

That’s, again, without “Megatron.” Rhodes and Johnson developed a brief rivalry, after Rhodes became the first and only player trusted by coach Mike Zimmer to shadow the intimidating target. In 15 career games against the Vikings, Johnson totaled 81 receptions for 1,095 yards and nine touchdowns.

Now, only five offenses have more passing touchdowns than the suddenly formidable Lions (16) despite the retirement of a future Hall of Famer. Five Lions have at least 25 receptions, including running back Theo Riddick and new receivers Marvin Jones and Anquan Boldin.

“In the past, you knew you had to stop Johnson,” Vikings defensive coordinator George Edwards said. “[Stafford] is spreading it around a little bit more and reading the coverages and not just kind of going to one guy.”

Priority, run defense

Zimmer wasn’t short on reasons for why the otherwise stellar Vikings defense sprung a leak, allowing 158 rushing yards Monday night in Chicago.

Zimmer pointed to missed tackles that led to a 69-yard run by Bears rookie Jordan Howard, which then led to players “freelancing” out of assignment. Then he pointed the finger at himself.

“I called a bad game. It was a terrible game,” Zimmer said. “Like, you’re a call behind all the time. You get a feel. I’ve done it for 100 years now.”

Fixing the run defense is a top priority this week, so the Vikings can get back to what they excelled at through a 5-0 start — rushing the quarterback. They’ve had just one sack in the past two weeks.

“It’s not like our pass rush isn’t there,” defensive end Brian Robison said. “We got hits on [Jay] Cutler last week, but the difference is they were able to run the ball. Our main focus has to be to stop their running game.”

‘Better communication’

Interim offensive coordinator Pat Shurmur said, initially, his plan is to call offensive plays from the sideline, not the coach’s booth.

“I feel better down [on the field],” Shurmur said. “In my opinion, it’s a better communication for the quarterback.”

So Shurmur will remain on the field where he has coached tight ends all season. Former offensive coordinator Norv Turner, who resigned Wednesday, used to call plays from the booth to quarterbacks coach Scott Turner, who would then relay the play to the quarterback.

McKinnon returns

Running back Jerick McKinnon returned to practice on a limited basis, marking the first time he has been able to practice since injuring his ankle Oct. 23 in Philadelphia.

Guard Alex Boone and linebacker Eric Kendricks were held out again Thursday, remaining in the concussion protocol. Defensive tackle Tom Johnson, also in the protocol, returned and was limited in practice.

Locke matured

Vikings punter Jeff Locke has fared well through seven games of a contract year. He’s on pace to set career-high marks in net average (40.0) and punts downed inside the 20-yard line (18), which is tied for third-most in the NFL.

“He’s matured,” special teams coordinator Mike Priefer said. “He doesn’t let one bad punt turn into four like he’s had in the past.”