Things could not get much worse for an ISU defense that was once known as the foundation of the team.

The unit gave up 583 total yards to Missouri in a 52-17 loss for the Cyclones (3-3, 0-3 Big 12) on Saturday, coming one week after giving up 607 in a loss to Baylor.

“I thought we tackled poorly for probably the first time Saturday down in Columbia,” said ISU coach Paul Rhoads. “But what [Missouri] did created a lot of space and too many holes. Even we had guys in gaps [where] there was space to operate.”

The ISU defense is ranked 108th nationally in total defense, having given up at least 400 yards in its three losses and allowing 447.17 yards per game through six games.

Iowa State has also given up 36.3 points per game — which ranks 115th among FBS schools — and an average of 46 points in its three losses to Texas, Baylor and Missouri.

Stopping the run has been especially difficult for the Cyclones, who have allowed a 100-yard rusher in four of six games. In the past two games, Iowa State has given up 129 rushing yards to Missouri’s Henry Josey and 200 to Baylor’s Terrance Ganaway.

“Gap assignments, we’ve failed to execute some of those,” said defensive end Jacob Lattimer. “When we failed, the other team has taken that opportunity, and they’ve gashed us.”

Defensive coordinator Wally Burnham said Sunday that the missed assignments have partly been due to his players having to accommodate adjustments by the opposing offense on the fly.

“They’d have the back out here and bring him in back in motion, we’d have to move and make adjustments on the run,” Burnham said. “It’s hard to get back to your gaps, get your reads when you’re doing it on the move and it becomes a very difficult situation.”

No. 17 Texas A&M (4-2, 2-1) will pose a major threat to Iowa State on Saturday, averaging 227.7 rushing yards per game, which is good for 16th in the nation.

A&M running backs Christine Michael and Cyrus Gray have already combined for over 1,000 yards on the ground, while they and quarterback Ryan Tannehill have combined for 17 rushing touchdowns.

“If you’re going to stop the run, you’re going to have to have enough bodies up there to stop him,” Rhoads said. “We’ll work hard with some different looks to try to get that accomplished.”

Johnson out for remainder of season

Shontrelle Johnson will likely be out for the remainder of the season, Rhoads said at his weekly news conference on Monday.

Johnson sustained a neck injury in the Cyclones’ 37-14 loss to Texas on Oct. 1, prompting him to sit out the next two games.

“Anytime you lose a starter on the football team, certainly when you lose your starting tailback, it’s a negative with your football team,” Rhoads said. “James White has been doing a fantastic job taking over that position and as is always the case with the running back position, you better have a stable group of them and Jeff [Woody] and Duran [Hollis] are picking up the slack.”

The true sophomore had 51 carries for 247 yards in four games started this season.

“Shontrelle, he’s a big-time running back,” said quarterback Jared Barnett. “He’s a great leader on and off the field. Not having him, I feel like it’s going to hurt us, but then we have a lot of depth in James White and Jeff Woody and Duran Hollis that can make up for what we lose in him.”

Texas Tech game time set

Iowa State’s Oct. 29 matchup against Texas Tech in Lubbock, Texas, will start at 6 p.m. and will be televised on Fox Sports Network.