Admittedly, the sample size is small. It’s been just over a week since the Wolves traded Jimmy Butler to Philadelphia for Robert Covington, Dario Saric and Jerryd Bayless. Since then Minnesota has played just four games, three with the new players.

But heading into Wednesday’s game with Denver at Target Center — the first meeting between the teams since the Wolves’ overtime victory in Game 82 last year that sent them to the playoffs for the first time since 2004 — the numbers are dramatic.

Since the trade the Wolves have been a top-five defensive team.

Let that sink in for a moment. The Wolves defense — dragging near the bottom of the NBA for much of this season after finishing No. 25 in efficiency last year, much of it while Butler was in the lineup — has taken a dramatic turn.

Since the trade the Wolves are No. 5 in defensive rating and points allowed and second in opponents’ field goal percentage. No coincidence, then, that the Wolves are 3-1 in those games.

“Going back through the film, I’d say our last four games has been our best stretch of defense,” said coach Tom Thibodeau, who brought a reputation for strong defense with him from Chicago but hasn’t found consistent success with the Wolves.

The question is, why?

After practice Tuesday, Thibodeau and some players cited a few factors:

• Improved play and evolving leadership of Karl-Anthony Towns and Andrew Wiggins;

• The defensive play of Covington, a small forward whose ability to guard three (or more) positions has allowed the Wolves greater freedom to switch on pick-and-roll plays. Covington was a first-team All-NBA defensive player last season.

• A good locker room atmosphere.

Butler, Wiggins and Jeff Teague all missed time early in the season for a variety of reasons. Thibodeau said having players out of the lineup on a regular basis hurt the team’s defense early on. So establishing continuity since the Butler trade has helped.

But, he said, there are signs that things are clicking defensively for Towns and Wiggins. Towns has averaged 16.5 rebounds during the four-game stretch and had a key block on the Pelicans’ Anthony Davis in a victory last week. Wiggins averaged two steals a game in the three Wolves victories since the trade.

“That’s important for us,” said Thibodeau, who said the recent stretch of defense from the two might be their best with the team.

Taj Gibson agreed. But when asked about the improved defense, he talked less about specifics and more about attitude.

“Just positive energy,” he said. “Everybody is on the same page. Everybody’s trying to do what they have to do. Everyone is filling in where they have to fill in.”

But Gibson also sees growth.

“KAT [knows] he has to do more,” Gibson said. “He’s been doing it. He’s having fun with it. His mentality, as a leader, is growing day by day. And Wigs has been really responsive.”

Towns said he was just trying to figure out when it’s best to lead by example or words. But the addition of Covington and Saric (the injured Bayless hasn’t played yet) drove home the point that he needed to help them fit in with the Wolves by giving them the best possible example.

“I just understand what it takes to make the team better,” he said. “I have to do my part. … It’s something you know. When you see the energy ticking down in practice, you have to pick it up. In the games, sometimes, you have to bring that energy when things are tough.”

The Wolves have held three of their past four opponents to 100 points or fewer. Even in Sunday’s loss to the Grizzlies, the problem wasn’t so much on the defensive end as on offense. With Covington leading the way, the Wolves created a lot of pass deflections. Denver will pose a good test, since the Nuggets rank No. 8 in the NBA in offensive efficiency.

“The communication, the tracking of the ball has been very good,” Thibodeau said. “So that’s definitely an improvement.”

Note: Keita Bates-Diop has been assigned to the Iowa Wolves of the G League.