The Lions drafted running back
While that versatility has shown through the first two weeks of camp, it's his ability to run between the tackles that's sticking out the most to coaches and teammates.
"He doesn't run the ball like a rookie," said fellow running back
"When I was a rookie, I wasn't as good as he is at running the ball. I was a natural playmaker, but I wasn't a natural in-between-the-tackles runner."
Riddick is fighting for a roster spot in a crowded Lions backfield that features established veterans like Bush,
"I think Riddick has really stepped in during training camp and done some nice things," head coach Jim Schwartz said. "Particularly in the passing game."
Riddick rushed for 917 yards and five touchdowns last year as a senior at Notre Dame, but also caught 36 passes for 370 yards and two more scores.
"I've been playing running back basically my whole life, so getting back there between the tackles, I feel comfortable," Riddick said after practice Wednesday.
"If there's a chance and an opportunity for me to bounce it (outside), then I'll bounce it, but in this league you have to go a lot more north and south than east and west."
There's usually an adjustment period that takes place before that kind of realization sets in for young runners, so Riddick seems ahead of the curve.
"I'm especially impressed with the way Theo is working," said Lions running backs coach and run game coordinator Curtis Modkins.
"I'd like to see it continue and see what happens when we get in the live bullets, but I've been impressed with what he's done so far, for sure."