From 1945 until 1981, Sammy Baugh was the only NFL quarterback to complete 70 percent of his passes in a season.

In one of the more out-of-place early NFL seasons, Baugh completed 70.3 percent (128 of 182) in eight games for the Redskins in 1945. The league average that year: 45.6.

Finally, in 1982, four years after sweeping rule changes liberated the passing game, Cincinnati's Ken Anderson completed 70.6 percent of his passes.

That stood firm until Drew Brees tied Anderson in 2008 and then surpassed him at 71.2 percent in 2011. Sam Bradford took it to 71.6 as a Viking in 2016 before Brees went to 72.0 last year.

Five games into the 2018 season, Vikings quarterback Kirk Cousins sits at 71.2 percent. He's on pace for third place all-time! And yet, among 2018 passers, he ranks … fifth?

"Who's ahead of him?" asked his backup, Trevor Siemian.

This conversation took place before Brees and the Saints played the Redskins Monday night. So the first name and number given to Siemian was, "Brees, 75.8."

"Wow," Siemian said.

Hours later, Brees raised his bid to 77.9 percent by completing 26 of 29 passes while breaking Peyton Manning's career record for passing yards.

Double wow.

Jared Goff (72.3), Derek Carr (71.3) and Eli Manning (71.7) also are ahead of Cousins. Seven passers are 70 percent or better, including Chicago pup Mitchell Trubisky (70.0).

About a decade ago, then-Vikings coach Brad Childress was talking completion percentages. He said the ideal target was 65 percent. The league average this year: 65 percent.

Monday, current Vikings coach Mike Zimmer was asked if he ever imagined a time when anything shy of 70 percent would be considered lacking.

"No, probably not," he said. "I remember when I was in Dallas and I believe we set a record [for opponent completion percentage] of 50 percent, or less than that. It's kind of uncharted territory now."

As are increases in penalties for roughing the passer, defensive holding and pass interference.

"Last year was the lowest scoring in the league in a long, long time," Zimmer said. "They wanted to fix that, and they obviously have.

"They're allowing things to happen — they're allowing receivers not to get touched, they're allowing quarterbacks not to get hit, they're allowing people to hold. There's a lot of things that when the league wants something, they're going to get it. I think they're getting it. That's not negative on the league, that's just the way life is."

There have been nine 5,000-yard passing seasons in NFL history. Seven have come since 2011.

This year, eight players — Goff, Cousins, Ben Roethlisberger, Brees, Carr, Deshaun Watson, Matt Ryan and Aaron Rodgers — are on pace for 5,000 yards. Goff is on pace to break Peyton Manning's record of 5,477.

Brees is going for his sixth 5,000-yard season. He also owns six of the top eight spots for most completions in a season. He has the top three, including the record of 471, which Goff, Cousins and Brees himself are on pace to break this year. Cousins heads into Week 6 riding the first four-game streak of at least 30 completions in NFL history.

When told that seven passers had completion percents above 70, Vikings safety George Iloka smiled and said, "And that number is going to keep going up.

"You watch," he added. "It's just how the league is designed. It's an offensive league. They want to protect those guys at all cost."

Siemian offered a rebuttal for his fellow offensive players.

"I know there's a lot of discussion about the rule changes, but I think it's a testament to some really good quarterbacks," he said.

"We're kind of fortunate to be seeing some of these guys play.

"There are so many things Kirk's doing so well. And he's making contested throws, too. A lot of his throws aren't just gimme throws. They're tight-window throws while he's operating from not the cleanest pocket. Talk about the rules, but we also have to realize that he's been super-impressive."

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