"It's a lot easier to play when you're having fun out there," Sims says. "When you're not having fun you make a lot of mistakes."
Part of the newly-found fun for the Auburn sophomore is the new defensive schemes brought in by Will Muschamp.
"I love it--great schemes for everybody," Sims says. "It's made for everybody to make plays. It's set up for everybody. We've got a lot of new schemes.
"We've got a three-man front, but it's really a four-man front because we have people blitzing. We've got lots of slants and I like to slant a lot because it's easier to get to the quarterback."
Sims is working at the noseguard and the three-technique positions with the first and second teams, and plays some defensive end when the defense switches to a 3-4. In a defense designed to make plays and force turnovers, Sims came up with a pick for a touchdown on a screen pass in 11-on-11 work in the Tigers' last practice on Wednesday.
"I've been waiting for one of those," the 6-4, 314-pounder says. "Hopefully, I can get one in a game so I can show my speed."
Pat Sims left the team last fall, but has been given a second chance with the the Tigers by Coach Tommy Tuberville..
Defensive tackles coach Don Dunn says he has been pleasantly surprised with the play of Sims, as well as another young defensive tackle who hasn't produced much on the field in the past, Tez Doolittle.
"Pat Sims is making progress," Dunn says. "I am really proud of him. The jury is still out. He is still on probation. Can he maintain the grind?
"Both he and Tez have had a good spring so far. We still have seven days to go. I want him to get better every day. That is what we are looking for, but so far he has been a real pleasure to coach."
One thing Sims has had to battle through this spring is problems with his right knee, which he had surgery on Nov. 16. He says the doctors had to repair torn cartilage and a meniscus tear.
"It had been like that since my junior or senior year (in high school) and I had never gotten it fixed," Sims notes. "I've been like this for a long time. If I keep it bent too long it's achy. I finally got it fixed, but it still hurts sometimes.
"It's not 100 percent, I can tell you that," he adds. "I go out there, try my best and do what I can do with my knee feeling like that."
Sims quit the team during the 2005 football season and admits he's not in football shape completely because of his knee surgery. However, he stayed in decent shape playing basketball, running and lifting weights.
While Sims was unsure of his future after quitting the team, it was a meeting between his father and coach Tommy Tuberville opened the door for a comeback.
"What really happened was, down in Florida we had a hurricane (Hurricane Wilma) and it tore up a couple of our (family's) houses down there," Sims says. "My parents were without lights for a couple of months. They decided to come up here. My father and my brother-in-law came up here and they called Coach Tub and wanted to have a meeting with him.
"That's how I got back on the team," he adds.
Now that Sims has his second chance, he says he's going to do his best to prove himself and help the team.
"I wouldn't be out here if I didn't think I could contribute," Sims says. "I believe I can come in and I'm competing for a starting position. Hopefully I'll get it by the fall. I'm still out here trying to prove myself, but I believe I'll be a great player for the team this year."