KNOXVILLE -- With 205-pound true freshman safety Brent Brewer entering the starting lineup and moving 181-pound sophomore Prentiss Waggner down to cornerback, the University of Tennessee's secondary got at least one small boost.

"Looking better coming off the bus," defensive coordinator Justin Wilcox joked.

In all seriousness, though, that size could make a difference at both spots for the Volunteers. Brewer was the first player weighing more than 187 pounds to start a game in UT's secondary this season.

Waggner, who teammate Chris Walker joked "probably weighs more like 165" since cutting off his dreadlocks last month, had been pairing with Janzen Jackson -- a 187-pound sophomore -- at the safety position. The other cornerback starters this season have been 186-pound redshirt freshman Eric Gordon, 185-pound junior Art Evans and 178-pound sophomore Marsalis Teague.

"Prentiss has got the size you like at corner, and Brewer is definitely a bigger guy at the safety spot," Wilcox said. "It changes some things."

First-year head coach Derek Dooley would like to go even bigger on the back end, though -- at least at safety. Some coaches have adopted a "four corners" philosophy in the secondary to match up with modern spread offenses, but Dooley isn't one of them.

"Not in this league," he said. "You better be able to come up there and hit a runner in this league. You look at the good teams we're playing, I think Alabama's safeties were about 220. They come up and strike you. You've got to have a bunch of corner guys, too, when it's time to cover. But you can keep those safeties from being exposed in space by your scheme or having a corner guy sit on the bench until it's third-and-10, and they put four wides in the game. Then put the little guys in.

"But when the big boys are in, you better have some big boys to match it. And if you don't, it's that old boxing match deal. It's going to hurt you."

In a perfect situation, Jackson would probably play corner. It's not that he's playing poorly or too timidly at safety. Far from it. In fact, safeties coach Peter Sirmon, a former NFL linebacker, said Jackson could "play any of the four positions in the back end ... and be incredible."

"But then who are you going to play at safety? That's the dilemma we're in," Dooley said. "Janzen really has position specifics for a corner -- his size, speed and everything else. But he's our best defender back there. When he's in the back end, he makes up for a lot mistakes ahead of him and getting guys down.

"When he's not in the back end, it hurts us."

Jackson said he'd be fine with moving to corner in the future -- "it pays more [in the NFL]," he noted -- and Waggner said he'd be fine with staying on the island. Waggner was initially recruited as an athlete who could play wide receiver, corner or safety.

"Going pretty well so far," Waggner said of the move. "There's a couple of little things I can improve on, like my angles to the ball and stuff like that, but I'm liking it. It's probably a little easier for me, honestly. The coaches say corner is Ferraris on Ferraris. You get beat, or you handle your business.

"I like to cover. It was fun competing against Alshon Jeffery."

Safety is much different, though. Dooley is a Nick Saban defensive disciple, and the Alabama head coach likes big safeties.

Even Brewer isn't big enough for Dooley's liking.

"He's at 205. He needs to be about 215," Dooley said. "But those good safeties are about 215. If you want to go tackle [Marcus Lattimore] and other good backs, you've got to have some stout safeties that can come up and hit. We're thin there."

Sirmon, not surprisingly, agrees with his boss.

"You'd like to have a guy that is versatile enough and strong enough that he can hold up throughout the season," Sirmon said. "A lot of guys -- you know, the smaller-stature guys -- get dinged up a little more. It's nice to have a little bigger safety. You'd like to have guys back there that can feel comfortable in the run fits. Guys that are 190-plus are guys that are a little more versatile, and they're guys you don't have to scheme around trying to protect them physically in the run game.

"Obviously, we'd like to have some more of those kind of guys."