"I did well in footwork, one-on-ones, i just did well."
Sims has been workign with area trainer Jack Eyer to shed weight and add strength simultaneously, and it has worked.
"I weighed in at 347, that's 20 pounds less than I used to be. And I'm stronger," he reported. "It really paid off."
While seemingly failing to lose a rep on Sunday, the Homewood (Ala.) offensive lineman made quite the impression on the Alabama staff.
"They were all shocked, they were glad to see my progress," said Sims. "They didn't want me any bigger, and I worked at it. Ate better, and they really see the change in my body, my prowess and my footwork.
"I was hoping every aspect of my game would be better, and it is."
"Alabama said to call them when the camp is over," he continued. "Alabama is still my top, I had a great day, I had certain feeling out there.
"Excitement, my parents love it, I love it. Bama is the clear number one an everyone else is behind."
Sims even earned a smile from Nick Saban.
"Coach Saban told me that he watched me do well, he was smiling the whole time he was telling me," he said. "He told me to not get bigger and I showed him that.
Coach [Mario] Cristobal was at work today, he said I looked great in all my drills. I still have work to do, but I improved, that's for sure."
Other players at the event and even their groups also took notice of Sims' work on this day.
"Some (Alabama) commitments that were there watched me, parents were telling me good job too," said Sims. "It made me think about all the hard work I have been putting in.
"I know Shaun Hamilton, he watched me and he said 'you know what it be.'"
While Sims put on a show, it wasn't because of a lack of talent on the defensive line.
"My toughest competition was Breiden Frehko. Daron Payne, too," said the rising senior. "We went at it, and I beat him. His strength is great, and he comes off the ball so quickly and uses his hands well. I just did what I was taught.
"Technique will take you a long way."
Cristobal then asked Sims to take some snaps at tackle to see if the trend would continue.
It did, even against the reigning defensive line MVP form The Opening.
"I went against Chad Thomas, he was tall and lean," said Sims. "He was good, but I beat him as a tackle. It's been a while since I got some reps at tackle."
Sims' "amazing" day at UA may end up as his final camp of the summer. The three-star plans on getting back in contact with Saban and company near the conclusion of the event this week. FOX Sports NEXT/Scout.com currently rates Sims as the No. 17 offensive guard nationally in the class of 2014.