TUSCALOOSA, Ala. — That exodus of NFL talent hasn’t made Alabama’s defense any more generous.

The top-ranked Crimson Tide still leads the nation in run, pass, scoring and total defense — just like last season. In fact, the numbers are all slightly better than last year’s national title group that drew speculation about whether it was ‘Bama’s best.

The Alabama’s doing it despite losing seven starters — three NFL first-rounders and four first-team All-Americans from the defense.

Tennessee coach Derek Dooley said it’s just part of Nick Saban’s assembly line of talent.

“They change jersey numbers, not guys,” Dooley said on Monday. “They sign the same guys every year, just different names. They draft. We recruit. And they get the first 25 picks of the draft.”

The Tide (6-0, 3-0 Southeastern Conference) undoubtedly faces its biggest defensive challenge in Saturday’s visit to quarterback Tyler Bray and the Volunteers (3-3, 0-3). The Vols rank 22nd nationally in total offense and 24th in scoring, compared to average rankings of 69 and 77 among Alabama’s first six opponents.

That doesn’t make Alabama’s stinginess much less impressive, even if the comparisons to past great defenses can wait.

The Tide held Missouri to 3 yards rushing last weekend and has five interceptions and eight sacks in the past two games.

Defensive end Damion Square attributes the success to how well young players like safeties HaHa Clinton-Dix and Vinnie Sunseri and linebacker Xzavier Dickson have stepped in for departed stars. Mark Barron, Dre Kirkpatrick, Dont’a Hightower and Courtney Upshaw were among the first 35 players selected in the draft.

“Those guys are playing excellent,” Square said. “It’s not the guys who have been out on the field for a while and played a key role in this defense for a while, it’s the guys that stepped in and took the place of Upshaw and Dont’a Hightower. Those guys are playing great football and that’s the reason our defense is playing the way it is.”

Linebacker C.J. Mosley and cornerback Dee Milliner are veterans who have moved into starring roles. Mosley had 12 tackles, a sack and a fumble recovery against Missouri to earn SEC defensive player of the week honors. Milliner and Ohio State’s Bradley Roby are tied for the national lead with 14 passes defended, including 12 breakups and two interceptions.

The statistical wealth is mostly spread around beyond them. Four players have two interceptions apiece and only Mosley has topped 26 tackles.

“It’s been a hard-working group,” Saban said. “They’ve had a really good attitude about what they want to try to do. I still think there’s a lot of areas that we need to improve on. We’re going to be challenged in a way that we’ve never been challenged by the quality of the offensive team that we’re playing this week in their capabilities in the passing game as well as the balance they have running the ball.”

Collectively, the numbers are more impressive and stack up well to the 2011 group. Alabama has allowed 55.3 rushing yards a game, down from 72.2 last season; 81 passing yards (111.5); 7.5 points (8.2) and 181.1 yards on average (183.6).

Saban said he doesn’t care about rankings and would just as soon change the subject, thank you.

“It only matters at the end, what was the whole body of work you could do on a consistent basis,” he said. “None of the rest of it matters. We’re going to play a lot better teams, and a lot better offensive teams in the future. And we’re going to be challenged in different ways. I’m concerned about reacting to those challenges properly. Not what we’ve done last week or the week before. So I’d appreciate it if we don’t have to talk about that anymore. Where we’re ranked, what we’re doing or what we did. I’m looking at what we’re going to do, if that’s OK.”

It seems to be OK with Alabama players, who are more outspoken about what they’re doing wrong than what they’re doing well.

“That’s instilled in us that you can always get better,” linebacker Trey DePriest said. “We haven’t put together a perfect game yet. It’s kind of unrealistic that we can put together a perfect game. It helps a lot, so we don’t get complacent. There’s no complacency. Each week we try to go out there and get better.”