"Our ball security is much better since the start of spring, but we had one on the grass today and I'm a little agitated," said Thomas, the Hogs' running backs coach.
"We have to come back tomorrow and need to improve. I tell them that's our lively hood. They can play defense if they don't take care of the ball."
Thomas said the ball security drills will be intensified on Tuesday when the Hogs practice just once. Running backs Kiero Small and Kody Walker knew that was coming.
"It's every day, but when we have one on the ground, Coach Thomas is going to fix it," Walker said. "Really, it's on us to police it, too. We hold each other accountable. If we see a ball away from the rib cage, we are going to tell each other about it before a coach does."
Small said, "Coach Thomas said the ball is the life line for a running back. It's not a good feeling when you see one loose. I think it goes through our entire meeting room when we have one. We believe in the razor grip, keep it high and tight."
Small didn't do any of the full speed drills on Monday after sitting out of the scrimmage Saturday with a sore foot. It's close to the spot where he broke his foot last year.
"I think I could have gone, but Coach (Bret) Bielema, our trainer Matt Summers and myself thought it was a good idea when it was sore to sit out a few days," Small said. "I'm not sure if someone stepped on it, I planted wrong, or what.
"Just better to get it feeling better now than to have it linger through camp. I don't think it's a big deal. It was feeling pretty good today and I might have been able to go, but everyone thought another day would be good for it."
Thomas said the grades for the scrimmage were good, but the standards are high and there are things to fix.
"We averaged 4.3 on yards after contact," Thomas said. "You keep doing that and you'll have indications that set up big plays. We have to keep working on that.
"We had six busts and that's not bad, but we strive for zero. Our top guy with YACs was JoJo Wynn but he had one nice run and only three carries. So that's how you get a good average. Alex Collins had the two explosion plays, the most of anyone."
There were no fumbles in the scrimmage, but a near miss cost Jonathan Williams a lap around the field. That's punishment for a loose ball.
"It came out late," Thomas said. "Too close for comfort. I told him to run a lap. If you lose one, you run a lap.
"I think that's a good reminder to stay focused. You come back tired and no one likes that feeling when you have to worry about executing on the next carry."
Thomas measures more than yards after contact. He looks for the "lost real estate" plays, too.
"We had too many," he said. "We want to eliminate those. We want to drop that by the next scrimmage. We are looking for better technique, focus to our system. They are going to see how that helps them follow the blocking."
Walker, who is spending about 30 percent of his time at fullback, said it's attention to the tracks that will lead to more big plays.
"We looked at that in the tape," he said. "I think we will get better at following the blocking if we stay closer to the right tracks."
Thomas said freshman Alex Collins had a good day, including his blocking.
"Really, all six of our backs are pretty good at the point of attack," Thomas said. "Alex could be worse at his blocking at the point of attack and I mean that as a compliment. He's decent, but not great and he's pretty good with his football IQ. He could play with more physicality there, but they all can do better.
"It's clear that Alex works in an inspired manner. He does not want to be the weak link (as far as blocking)."
Walker said he's had good luck with his repaired broken leg so far. He's missed no time after being cleared late in spring drills.
"It feels good and I'm trying not to think about it," Walker said. "It's not bothered me at all and my goal is to make it through camp without thinking about it. I'm working to take good care of it."