Grimes came off the bench for five carries and 23 yards and two catches for 12 yards.
“He’s a smart guy that embraces his role,” O’Brien said. “He can catch the ball, and he’s one of our core players on special teams.”
Polk had seven carries for 36 yards, a 5.1-yard average per carry. He also caught five passes for 34 yards.
“Polk had a pretty good game,” O’Brien said. “He showed some juice in the running game. He caught the ball well, too.”
The Texans finished with 24 carries for 71 yards, a 3-yard average.
Polk is a bigger back who would likely be a change of pace or short yardage guy while Grimes may be more of a true backup to starter Alfred Blue.