So much for conventional wisdom.

Heading into Seattle’s game at St. Louis on Monday night, it was easy to look at the stats, which showed Seattle second in the NFL in rushing and the Rams 30th in the NFL in run defense, and think Marshawn Lynch might have a big night.

Instead, the Seahawks tailback finished with just 23 yards on eight carries, his fewest since managing just 11 on six carries on Sept. 18, 2011, a 24-0 Seattle loss at Pittsburgh.

The Seahawks finished with just 44 yards rushing on 15 carries as their offensive line was largely dominated by St. Louis’ defensive front. That was also Seattle’s fewest rushing yards since getting 31 in that same Pittsburgh defeat.

“There was nothing happening in either phase, run or pass,’’ said Seattle coach Pete Carroll. “We couldn’t do anything. Just a tremendous night for those guys on defense.’’

Lynch’s irritation seemed to boil over during a sequence in which Seattle scored its first touchdown in the second quarter.

Seattle needed three plays to score from the 1-yard line, with two Russell Wilson runs failing to get the ball in before Wilson then hit Golden Tate with a 2-yard scoring pass.

Lynch could be seen gesturing in apparent frustration as he came off the field.

Carroll brushed off Lynch’s actions afterward.

“He’s a competitor,’’ Carroll said. “He wants the ball. He wants to put the ball in the end zone. He wants to help us win. He got the ball eight times tonight — he didn’t have a chance tonight. And we couldn’t get him the football. It had nothing to do with anything other than that.

“He was frustrated by that and I am, too. We are both frustrated. We were sitting on the sidelines together frustrated.’’

Even when Seattle scored, it came with what coaches like to call a “teachable moment’’ as Tate was called for taunting as he waved at St. Louis defenders for the last 30 yards of an 80-yard TD in the third quarter.

Tate drew a 15-yard taunting penalty that was enforced on the kickoff, which Carroll termed “not the way we want to play.’’

Tate said he simply got caught up in the emotions of what had been a hard-fought game.

“The receivers and DBs were chirping all day,’’ he said. “Made a heck of a play and emotions got involved quickly. I knew I had nothing but field and I let my emotions take over. … I let mine get too high. A lesson learned. I’ve got to learn from that. If I want to be a great player like Larry (Fitzgerald) and Demaryius Thomas and Calvin Johnson I’ve got to act like I’ve been there before.’’

Tate said the emotions were due in part to the fact the Seahawks and Rams have played pretty tense games the past few years.

“Every time we come to St. Louis it’s just a battle,’’ he said. “After the game I found those guys and said, ‘Hey, we are men out there playing football, it’s physical, it’s competitive. There are no hard feelings on my part. Mad respect for you guys.’ I’ve just got to control my emotions.’’

Seattle receiver Sidney Rice, who has been dealing with knee issues since training camp, left the game in the second quarter with what was initially reported as a knee injury.

Carroll later said Rice both “banged his knee’’ and also his head.

Asked how long Rice might be out, Carroll said, “I don’t know that.’’