David Cobb wouldn't allow himself to be tackled. Not when the first Michigan defender hit him 3 yards behind the line, or when the second one lunged at his legs and slipped off.

Cobb kept plowing ahead after a third Michigan player dived and bounced off him. A fourth guy grabbed his shoulders and spun him. Nope.

A fifth defender tugged on his shoulders, too. Nothing.

The sixth guy latched on to Cobb's waist. Nada.

A seventh defender joined the mass of moving bodies and Cobb finally fell to the ground.

But not before gaining another 3 yards.

Minnesota running back David Cobb (27)

"When you get in one of those zones," Cobb said, "it's unexplainable."

Actually, Matt Limegrover, Gophers offensive coordinator, found that particular 20-yard run easy to explain.

"That's what he's done for two years now," he said. "He's carried us on his back."

Cobb's 2014 season ranks among the best ever statistically by a Gophers running back. He needs 114 yards to tie Laurence Maroney's single-season rushing mark of 1,464. He's 54 rushing attempts shy of Thomas Hamner's record of 308.

He's tied for seventh with 11 rushing touchdowns and could move up the charts with two regular-season games remaining.

An appreciation for Cobb's performance begins with his running style. He doesn't have blazing speed. He's not massive in size. He's not as electric as a few other elite tailbacks in the Big Ten.

Cobb succeeds because of toughness as much as his talent. He runs hard and with purpose. And heart. Yeah, especially heart.

"My biggest thing is," he said, "never let one guy tackle me."

That credo became evident this week after watching all 254 of Cobb's runs this season in slow motion for 2½ hours on game and coaches video at the team's facility.

By my count, Cobb has broken 97 tackles and accounted for 896 yards after contact. As a metric, yards after contact can be interpreted differently. For this exercise, we counted every time Cobb was touched, whether it was a big hit or a futile one-handed tug at his jersey as he ran through a hole.

In clip after clip, Cobb refused to quit on runs. He displayed both an ability to break long runs and to make something of nothing. Extra effort is his standard gear.

"It takes a lot of heart and a lot of toughness to continue to run through tackles 25, 30 times week after week," he said. "If you love it, you enjoy it."

Cobb loves it, judging by the way he pinballs off defenders and pushes the pile forward. On numerous runs, he was hit behind the line but managed to avoid negative yardage. Those hidden yards are easy to overlook but they've kept the offense out of undesirable spots.

It's not uncommon for Cobb to gain 6 yards after contact on what is recorded officially as a 3-yard run, a trait that Limegrover readily admits makes his offensive line "look good" or sometimes better than it probably should.

"He's probably not our strongest running back, but he runs the strongest," Limegrover said. "It's a unique thing. He has a great mindset that he's not going to be denied."

Two runs this season reflect that. First, that ridiculous one against Michigan seconds before halftime. Cobb kept breaking tackles and carrying defenders on his back and straining for extra yards, making one wonder if he had been guaranteed a free trip to Maui if he reached the end zone.

Cobb calls it the best run of his career "by far."

"I don't know how I did it," he said. "It's a lot of adrenaline."

His 6-yard touchdown run against Iowa offered less flair but similar substance.

Cobb quickly recognized he had nothing up the middle after taking the handoff. He bounced the run to his left, but an Iowa defender closed on him at the 9 for what could have been a negative play. Cobb broke free with a stiff arm and then split two defenders near the goal line.

His effort was the difference between a touchdown and a 3-yard loss.

"Our linemen can't block them all," he said. "Sometimes it's on us to make a guy miss."

Gophers coach Jerry Kill cited Cobb's patience as his best attribute as a runner. Cobb chose patience and vision. Limegrover had a hard time singling out one quality above the rest.

"Is there one signature thing? No," he said. "But that's not a bad thing, either."

How about determination? Yes, that's harder to quantify and can't be measured like size and speed.

But that's my lasting impression after watching 97 broken tackles on 254 runs.

Chip Scoggins • chip.scoggins@startribune.com