Even so, it wasn't a surprise to Illinois State coach Brock Spack when Roberson moved to cornerback and signed with the Vikings in 2016. Spack could recognize the abilities that Roberson had for that position. Sure enough, those traits led Roberson to success in the Canadian Football League and now an opportunity in the NFL.
The Bears signed the 27-year-old Roberson to a two-year deal last week. The addition came after Roberson recorded seven interceptions with the Calgary Stampeders last season and emerged as one of the CFL's top cornerbacks.
"He's such a good athlete," Spack said on the Laurence Holmes Show on Tuesday. "He's built like a big-time corner. He's tough, and he loves football. It's hard to find guys who want to play defensive back that have that kind of ability to play in the National Football League. It's hard to find them, because you got to have some length, some speed, change of direction and all that stuff and you got to be smart. There's a lot of things you do coverage-wise now.
"He's able to play in a lot of space. It's a passing game, and the corners are kind of on an island so to speak. They end up playing their own game. You got to be able to cover, play a lot of space, a lot of grass. If he can do that in (the CFL), I think you have a chance to do it down here in the states."
A transfer from Indiana, Roberson was Illinois State's quarterback in 2014 and 2015, over which the Redbirds went 23-5. Illinois State lost 29-27 to North Dakota State in the FCS national championship at the conclusion of the 2014 season.
Roberson had 10 interceptions across 32 regular-season games for the Stampeders in the last two seasons. Previously a defensive coordinator, Spack saw the potential of his quarterback Roberson as a cornerback long ago.
"Tre's a tough kid," Spack said. "We ran him quite a bit here, he ran with the football, so he can take a shot, make people miss. That's what you kind of have to have as a corner, you have to kind of make blockers miss sometimes and you have to have a great change of direction to make blockers miss in space.
"He looks like he can get some people on the ground. He's such a good athlete, it doesn't surprise me. He's not afraid of contact. We ran him quite a bit with the football in his hand here. He's tough.
"He's been prepared for that."