Jim Souhan
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– The Vikings brought four quarterbacks to London and three practiced during the team’s workout Thursday next to a cow pasture.

If their game Sunday goes as expected, they will by this time next week be choosing between their injured franchise quarterback, the injured franchise quarterback they acquired to replace the former, and a quarterback who will have won five of the seven games in which he has played this season.

This is where it is important to be able to distinguish between fish, and chips. The Vikings need to be wise enough to discern which quarterback is an entree, and which is an accompaniment.

Sunday, the Vikings will face the Browns, the likely originators of the term ‘‘Brexit,’’ for the ability to leave a division race by the end of September every year.

The Browns have lost 22 of their past 23 games and are getting worse by the week. They will be without their best player, tackle Joe Thomas, and without their best young player, first-round draft pick Myles Garrett, who is in the NFL’s concussion protocol.

The Browns’ historic ineptitude could complicate the Vikings’ decision. Current starter Case Keenum will not need to play well to win on Sunday. Would the Vikings replace a quarterback who is winning with a quarterback recovering from a knee injury?

Keenum, Teddy Bridgewater and Kyle Sloter practiced Thursday. Sam Bradford did not.

Asked whether Keenum would start Sunday despite a chest injury, Zimmer said, ‘‘We’ll see.’’

Asked how Bridgewater has looked, Zimmer said, ‘‘Well, today, he didn’t do much but he did quite a bit yesterday before we left and he looks good.’’

Zimmer and Vikings General Manager Rick Spielman have developed a strong roster that has experienced no postseason success. Keenum might be the easy choice to win games in November and December. The Vikings need to play the quarterback who will give them the best chance to win in January.

Like pitcher victories in baseball, quarterback victories can deceive. Even factoring in his one brilliant performance, in the Vikings’ 34-17 victory over Tampa Bay in September, the Vikings are averaging fewer than 20 points in games in which Keenum plays this season.

His record in games in which he has played this season is 5-2, placing the Vikings among the top teams in the league, but his game-by-game synopsis is less impressive.

He played poorly against Pittsburgh, brilliantly against Tampa Bay, poorly against Detroit, and well enough in games against Chicago, Green Bay and Baltimore.

He threw for 369 yards and three touchdowns against a Bucs defense missing three of its best players. Since then, he has not thrown a touchdown pass to a wide receiver, has thrown two touchdown passes and two interceptions, and has not topped 239 passing yards while missing receivers deep, either with his arm or eyes.

On a team relying on defense and rushing, Keenum has been good enough to win against the soft portion of the schedule. The Vikings have faced rookie Mitch Trubisky, Packers backup Brett Hundley (after Aaron Rodgers was injured) and slumping Ravens starter Joe Flacco during their three-game winning streak. Keenum has done his job by not losing games that the defense was capable of winning on its own.

What we’ve seen this season is exactly in line with Keenum’s career.

What is underappreciated about good NFL quarterbacks is that every week a team of defensive experts picks apart their flaws. There might be 50 quarterbacks in the league who can play well for a game, perhaps even a few weeks. There are maybe 20 or so who can survive the scrutiny of serial defensive game plans. If Keenum is among the 20, he has yet to prove it at the age of 29.

Sticking with Keenum might feel safe, but the organizational goal is not to slip into the playoffs but to win a Super Bowl. Keenum can’t get the Vikings there. Bridgewater or Bradford, if healthy, would give them a puncher’s chance.

Jim Souhan’s podcast can be heard at MNSPN.com. On Twitter: @SouhanStrib. • jsouhan@startribune.com