One-on-one, it can sometimes be hard to hear Jeff Casteel.
The Arizona Wildcats defensive coordinator will cross his arms, tilt his head down and speak in a tone that's barely louder than a strong whisper.
During practice, however, it's pretty much the exact opposite. Casteel's players always know where he is.
"He has a little bit of a different style because he'll get in anyone's face," linebacker Jake Fischer said. "It doesn't matter if you're a fifth-year senior or a true freshman. He'll get on you if he doesn't see you working."
The veteran coach - preparing his for his 12th season as an FBS defensive coordinator - demands perfection on the field. Which, for a defense that last season gave up 499 yards per game and more than 35 points per contest, isn't always reciprocated.
But that doesn't mean the Paden City, W.Va., native is going to stop asking for it.
"The only way we're going to get better is by getting reps," Casteel said. "We have to learn from them and get it right."
Enter spring football.
Casteel, in his second season with the Wildcats, is hoping Year 2 is smoother and more productive than his debut season.
He's using spring ball as his entry point. He's more comfortable in Tucson and his players are more versed with his 3-3-5 formation.
"I think the players have a better understanding of what to expect from us," Casteel said. "And I think we as coaches learned a lot about them."
Casteel said the UA's rush defense, which gave up 206.2 yards per game last season, was a major area of concern in Year 1. While spring should be a time for relaxation and repetitions, Casteel and his players are dead serious.
And then there are the injuries, which are a major issue.
Casteel is trying to drastically improve the defense without several of his best players. Marquis Flowers, who led the team last year with 13 tackles-for-loss and 5 1/2 sacks and was second with 100 total tackles, won't practice this spring after undergoing shoulder surgery.
Starting cornerbacks Jonathan McKnight and Shaquille Richardson are both limited with shoulder problems as well. Defensive tackle Dan Pettinato is out for an extended period with a knee injury.
"We didn't have a lot of depth last year and our kids had to take a lot of reps," said Casteel, who doubles as the linebackers coach. "They played a lot of football and started wearing down in the final six or seven games.
"The one good thing is that we will get our young guys some reps, which will help our football team down the road."
But don't be surprised if you hear some yelling coming from Kindall/Sancet Stadium in the meantime.
"Of course I'm biased, but I think he's the best linebackers coach there is," coach Rich Rodriguez said. "He's pure football and I think his players really respect him."
• March 29: Scrimmage, 7 p.m. at Phoenix College
• April 13: Spring game, 1 p.m. at Kindall/Sancet Stadium
Contact reporter Daniel Berk at email@example.com or 573-4330. On Twitter @DSBerk.