This is the rare story about the Vikings and grass that will contain no Percy Harvin jokes.

The Vikings are lousy when they play football on real grass. You may think that is irrelevant, or obvious, or par for the course. But it's not any of those things.

This season, the Vikings are 9-1 on turf and 0-3 on grass. That is not unusual. Since they moved from Met Stadium into the Metrodome in 1982, they have been stunningly bad when playing on grass fields.

On Sunday, the Vikings will play their last regular-season road game of 2019 on grass, against the Los Angeles Chargers.

They will be challenged by Philip Rivers, Melvin Gordon and a time change — and by the field surface at Dignity Health Sports Park. History indicates this game could be far more difficult than the teams' records — the Vikings are 9-4, the Chargers 5-8 — would suggest.

Vikings legends were built on the grass, snow and slop of old Met Stadium. Watch highlights of Fran Tarkenton scrambling or Jim Marshall rushing the passer, and you will gain a renewed appreciation for players of that era. It's not easy to play football in quicksand.

The team moved into the Metrodome in 1982 and has played all home games on turf since. Only three teams playing home games in enclosed stadiums have won Super Bowls — the 1999 St. Louis Rams, 2006 Indianapolis Colts and 2009 New Orleans Saints.

According to the website Pro Football Reference, since 1982, the Vikings' winning percentage on grass fields is .390 (66-104-2). That ranks them 25th among the 32 NFL franchises, and lower than Jacksonville, a traditionally downtrodden team that plays its home games on grass.

There are mitigating factors here. The Vikings play at Green Bay every year, meaning they have faced either Brett Favre or Aaron Rodgers in almost every game at Lambeau since the early 1990s.

So let's look at another illuminating stat: how playoff-qualifying teams perform on grass. Since 1982, Vikings teams that made the playoffs posted a combined 40-46 record on grass in those seasons, ranking 31st of 32 teams. The only team worse: the Detroit Lions.

Again, being forced to play so many good teams at Lambeau affects these numbers. What might be more telling is the Vikings' road struggles against the Chicago Bears. The Vikings have lost 16 of their past 19 games on Soldier Field's sandy, patchy surface and are 13-24 overall there since 1982. Favre's 2009 Vikings went 12-4 but lost at Soldier Field to a Bears team that would finish 7-9.

What explains this?

Vikings teams, like most turf teams, have valued speed and quickness. They are typically strong at receiver and defensive end, two positions at which slippery footing can be troublesome.

During training camp and early in the season, the Vikings practice on grass, outdoors. When the weather turns, they practice indoors on turf. They may enjoy playing on grass in the sun on Sunday, but they may not enjoy the results.

"I mean, we'd rather [practice] on grass, obviously," Vikings coach Mike Zimmer said on Wednesday.

"It's an adjustment, but it's something we just get used to," cornerback Xavier Rhodes said. "It's something we've played on since we were little kids. But it's pretty tough when you've been playing on one type of field, and then switching to another. It's all just about playing football and keeping your feet beneath your frame. Once you're able to do that you can play without slipping or falling."

The Vikings are 6-0 at home and 3-4 on the road. Their only loss on turf was on a Monday night in Seattle. They are in a playoff position with three games to go. If they remain a wild-card team, they might need to go win a game on the grass of Green Bay or San Francisco.

Their average margin of victory at home is plus-13.5. On the road, it's plus-1.3. One slip of the foot on a soft patch of grass, and a game — or a season — can be lost.

Jim Souhan's podcast can be heard at On Twitter: @SouhanStrib E-mail: