SANTA CLARA, Calif. -- What do you think was a bigger challenge for Eric Mangini -- prepping for his cameo on The Sopranos a few years back or scheming this spring a San Francisco 49ers defense that lost six regulars this past offseason?

"Well, since I didn't have any lines in The Sopranos…" Mangini said at the conculsion of the Niners' minicamp last week, his voice trailing off as a smile crept across his face.

Indeed, you might say that neither caused as much consternation for Mangini as did his first two years with the 49ers. Because for the past two seasons, first as a senior offensive consultant, then as the team's tight ends coach, the artist formerly known as Mangenius was like the proverbial fish out of water in landlocked Santa Clara.

"Offense is a little bit out of my wheelhouse," Mangini said with a laugh. "It had been since, I think '94, since I had coached offense, maybe '95. So I was doing everything I could to make sure I was on top of what we were doing offensively and then helping our guys look good."

And, of course, when he wasn't working with the likes of Vernon Davis, Mangini looked across the room to see a dominant unit that led the Niners to three straight NFC title games and a Super Bowl appearance … before last year's letdown.

So as rookie coach Jim Tomsula's first defensive coordinator, Mangini is back in a comfortable place, albeit without players like defensive end Justin Smith, inside linebackers Patrick Willis and Chris Borland and cornerbacks Chris Culliver and Perrish Cox.

"Going through camp with those guys, you respected how talented they are, how they worked, their toughness, watching the games, the plays they made. Loved that part. And not just the raw talent … watching the way they performed, watching the way they dealt with adversity, situations, things like that. You know how hard it is, and the respect of how well they did it."

Under Vic Fangio, and despite dealing with an inordinate amount of injuries, the Niners still had the No. 5-ranked total defense last season for an 8-8 team.

Mangini will maintain Fangio's 3-4 scheme. Besides, Mangini and incoming senior defensive assistant/linebackers coach Jason Tarver are 3-4 guys at heart, and the returning personnel are already familiar with the alignment and assignments.

"The general 3-4 system allows you to be specific with four guys together when needed, or the outside linebackers and the D-line together, when needed," Tarver said. "So it allows you to get more exact on your coaching and work together. That's been a good process."

The way strong safety and last year's team MVP Antoine Bethea put it, Mangini's defense is all about confusing offenses.

Mangini, who cut his coaching teeth under Bill Belichick, first with the Cleveland Browns and then the New England Patriots, was not about to dispute that description.

"I've always been a big believer in having versatility," Mangini said. "That's why, the 3-4 in general, I think it's a balanced set so you can do whatever you want to do and you cannot be forced into certain things because of the [versatility] of the defenders.

"But then you have to have guys that are flexible, both physically and mentally, so that you can take away things the offense is trying to do. You can attack weaknesses, you can attack players. That flexibility is huge for me."

It's been a staple of Mangini throughout his career, which included head coaching gigs with the New York Jets (hence The Sopranos appearance) from 2006 through 2008 and the Browns in 2009 and 2010 (he was an ESPN NFL analyst before coming to the Niners in 2013).

So what's Mangini's scouting report on his defense after the offseason training program, some six weeks before training camp?

"Really really impressive outside linebackers," he said. "Good young and veteran defensive linemen. Really enjoyed working with [inside linebacker] NaVorro [Bowman], him coming back from his injury, and Mike Wilhoite has been fantastic in the room and the things that he's done.

"The secondary, another mix of guys where, some are a little bit older, some are sort of in the youngish part of their career. We've got a couple of new young kids that have a ton of talent, which is great, too."

Almost as great as feeling comfortable in your job description again.