To watch the St. Louis University basketball team play defense — to watch the Billikens grind one opponent after another into offensive oblivion, denying shots, forcing bad shots, causing turnovers — you would think it was something they were born to do, that defense is part of their DNA.

You picture them screening roommates away from the bathroom mirror or forcing them to eat meals with their off hand.

You picture them as loving defense, as guys who in high school were voted most likely to run into a brick wall. That is not the case. It’s an acquired taste.

“Honestly, I did not play defense (in high school),” said forward Grandy Glaze. “I was just an offensive-minded kind of guy. If a guy missed a shot, I thought that was good defense.”

“I’m still a work in progress, learning to love it,” forward Dwayne Evans said. “It’s kind of a necessary-evil kind of thing. It has gotten more fun over the years. Especially when you’re getting three, four, five stops in a row and that’s leading to transition buckets, the energy starts building up. It gets real exciting out there.”

Now, they know what good defense is and things are starting to get pretty exciting. Two-thirds of the way through the regular season, SLU ranks sixth in the nation in what the NCAA calls scoring defense — fewest points allowed — at 58 points per game. Its 3-point shooting defense ranks seventh, holding opponents to 27.5 percent. On all shots, the Billikens rank 19th, with opponents shooting just 38.6 percent against them.

It’s one of the reasons SLU was talked of as a Sweet 16 team last season and that talk is picking up speed again this season.

When you factor in the pace of a game — slower-paced games naturally have fewer points — SLU’s defense looks even better. When you consider points scored per possession, which is tracked by basketball analyst Ken Pomeroy as adjusted defensive efficiency, SLU has the nation’s top defense this year, allowing just 86.7 points per 100 possessions against an average offense. (Ohio State is second at 87.3, followed by Arizona.)

Not only is that the best in the nation right now, but over the past 12 seasons for which Pomeroy has data on his website, kenpom.com, it is the seventh-best mark. That number, of course, could get worse as SLU faces some of the better offensive teams in the Atlantic 10 in the weeks ahead, but the way 19th-ranked (and rising) SLU (18-2), winners of 12 straight and 5-0 in league play, is going, maybe not.

“Honestly, I don’t know that they’re missing anything on defense,” said former NBA coach Stan Van Gundy, who now works on Atlantic 10 games for NBCSN cable. “They’ve got everything you want. … I think they know how hard they are to play against, know how frustrating they are. I think they enjoy that a lot.”

They enjoy it and respect it. They realize they have created an identity for the team and hold it dear.

As for the answer to how a group of guys who used to be largely ambivalent about stopping the other team learned to stop worrying and love defense, the answer is pretty simple. They didn’t have a choice.

“(Former SLU) coach (Rick) Majerus was such a defensive-minded coach,” said forward Rob Loe. “He taught us defense first, that you’ll only get on the court if you play defense. That’s changed the way I look at the game. It’s more defense now than offense. If you want to play, you have to learn the fundamentals of defense.”

“From the get go,” recalled Kyle Cassity, part of Majerus’ first recruiting class who graduated two years ago, “he would let you know, you can score all the points you want to score, but if you don’t guard somebody you’re not going to see the floor. Coach would quote things like, ‘You score 20 but you give up 22. You’re still negative two.’ That was from the very beginning and I’m sure coach (Jim) Crews has held them to that because he and coach were close. It’s something I think hopefully is going to stay in the program for a long time. Crews preaches it just like Majerus did. ”