Tyrone Swoopes looked near unstoppable on opening night in Texas’ 50-47 upset win over Notre Dame. The senior quarterback bulldozed through Notre Dame defenders on 13 carries, finding the endzone twice.

His last carry of the night was a six-yard touchdpwn scamper up the middle to give Texas the victory. While Swoopes didn’t start against the Fighting Irish, his impact was undeniable in the Longhorns’ signature win.

“We’re going to line up and we’re going to let the 18-wheeler just run over people,” head coach Charlie Strong said after the victory. “He came in there with his package and we knew he was going to play.”

That 18-wheeler package looked to be a primary piece of Texas’ offense after week one. But five weeks into the season, Swoopes’ involvement in the offense has decreased dramatically.

Swoopes has not eclipsed ten carries in a single contest since that opening-night upset, averaging just 4.5 rushing attempts per game. He reached pay-dirt twice in a 49-31 loss to Oklahoma State in week four, but has been shut out of the end zone in Texas’ three other matchups.

The advent of the 18-wheeler package came in 2015, after Swoopes was demoted from the starting-quarterback role. After losing the role to then-freshman Jerrod Heard after week one, Swoopes, relegated to the bench, was unsure of his future with the program.

But he returned to the Longhorn offense three games later, serving as a short-yardage specialist against Oklahoma State. The Longhorns ultimately lost 30-27, but Swoopes role with the offense was reborn, thanks in large part to a seven-yard touchdown in the second quarter.

“I was excited to get another chance to get on the field and help the team out,” Swoopes said following the loss. “I’m just staying ready… If something were to happen, then I just kind of pick up where I left off.”

Swoopes’ success continued in the Longhorns upset win over undefeated Oklahoma a week later at the Cotton Bowl in Dallas, with the then-junior throwing for a touchdown as well as running for one. By the end of the 2015 season, Swoopes had accumulated 12 touchdowns on the ground, rushing for 451 yards on the year.

After competition for the starting quarterback job in preseason, Swoopes ceded the role to freshman Shane Buechele. While Texas now sports a new system installed by offensive coordinator Sterlin Gilbert, Swoopes’ role within the offense remains the same: run it up the middle, and dare a defender to bring you down.

Five games into the 2016 season, defenders have proved more adept at driving Swoopes to the turf. He is still a load to tackle at six -feet -four inches and 249 pounds, but not an immovable force against multiple defenders.

An explanation for the struggles of the 18-wheeler comes from the defenses facing it. Most teams have come to recognize what will occur when Swoopes enters the game, as have stacked the line of scrimmage accordingly. Instead of seeing six defenders in his face before snapping the ball, Swoopes is now seeing eight or nine opposing jerseys.

“What they did is they over-loaded the box,” Strong said on Monday. “They’re playing really tight. Everyone have seen it and if you see it enough, people can adjust to it.”

The 18-wheeler package is still a potent force for the Longhorn offense, and a tool for generating significant yards and points within the redzone.

But it has gotten predictable, and has become easy read for opposing defenses. Now, it must adapt if it wishes to survive and aid the Longhorn attack moving forward.