ANN ARBOR -- Michigan basketball assistant coach Luke Yaklich was watching hoops in his living room with his wife, Amy. The Wolverines would play Indiana in a few days, and Yaklich's mind was on ball screen defense. Amy asked a question, and then another, and Yaklich realized words alone wouldn't suffice.

"So I started moving some furniture around," Yaklich said. "I had to get the screener and the ball handler set. We did some 'hedging,' some 'whiting,' some 'icing' -- we did it all."

Welcome to Yaklich's world: all defense, all the time. His devotion has paid off for undefeated Michigan, ranked second in the country largely because it excels at stopping the other team from scoring.

John Beilein, in his 40-plus seasons as a head coach, has mostly been known for his innovative offense. After the 2015-16 season ended, he decided his program's defense needed an upgrade. He hired a new assistant, Billy Donlon, with that in mind. Michigan made some strides defensively but Donlon left after one season. Another U-M assistant had left several days earlier. It was the summer of 2017 and suddenly Beilein had two vacancies to fill.

His diligence and patience led him to hire two assistants from Illinois State: DeAndre Haynes, who would work with Michigan's guards, and Yaklich.

Yaklich had something in common with Beilein: both had once been high school coaches and taught social studies. And like Beilein, there was a time Yaklich thought that would be his last job.

"I really stuck to that adage, 'Be where your feet are,'" Yaklich said on Sunday, a couple of hours before Michigan beat Indiana at Crisler Center. "Each coaching and teaching job I was at, I remember feeling, 'I'm going to retire from this job.'"

Yaklich was coaching the boys' varsity team at Joliet West High School in Illinois when a job opened on Dan Muller's staff at Illinois State. Yaklich had been a student manager for the program when Muller was a player, and the two remained friends. Muller hired Yaklich in 2013.

In his 14 seasons at the high school level, Yaklich wanted his teams to be known for their man-to-man defense. At Illinois State, he found himself underneath the basket during drills, eyes and ears on the defensive players.

"You always come back to who you are," Yaklich said.

Halfway through his first season at the college level, Muller said, "OK, Luke, you've got the defense." All the assistants shared scouting duties, but Yaklich became the voice of the defense at practice and in games.

Illinois State was ranked 89th in adjusted defensive efficiency, per KenPom.com, the year before Yaklich arrived. His final season, the Redbirds were 19th.

Beilein noticed, and brought him to Ann Arbor before last season, making him the de facto defensive coordinator. Beilein has called him the "Minister of Defense." Michigan won a program-record 33 games and reached the national championship, its defense finishing the season as the third-best in the country, by the far the best of the Beilein era. Michigan ranks fourth in that category this season through its 15-0 start.

Yaklich's philosophy boils down to forcing the opponent into difficult 2-point shots. What Beilein and other smart coaches have always tried to generate for their offenses -- open 3s and layups or dunks -- Michigan is now hell-bent on preventing.

These Wolverines have been drilled to "contest every shot with every fiber of their being," as Yaklich, 42, says. To do that, another Yaklich motto -- he likes mottos -- comes into play: "What gets measured gets done."

With the aid of the team's student managers, Michigan charts every possession in practice as well as games. Defensively, that includes the rate at which Michigan contests shot attempts.

There is no strict definition of a contested shot, but coaches know one when they see it -- essentially, a hand close enough to the ball at its release to affect the shooter -- and Michigan's managers have been trained to tell the difference. Michigan's goal is to contest 75 percent of shots. "When we're between 80 and 90 we're pretty damn good," Yaklich said.

It's important that defenders can stay in front of the players they're guarding. "Guard your yard," Beilein says. Physical tools help there. Michigan's starting point guard, Zavier Simpson, is strong and quick. Small forward Charles Matthews is strong and quick and long. Center Jon Teske, despite his 7-foot-1, 260-pound frame, moves his feet well.

"Having good feet, being able to slide laterally, that is huge," Yaklich said.

Asked if there's a non-negotiable physical trait for a good defender, Yaklich mentions something that might not be a physical trait at all: grit. "That grit part is that intestinal fortitude that 'I'm here and I'm going to win my matchup.'"

Help may be a good thing in daily life, but relying on it defensively is dangerous.

If a defender is beat off the dribble, a teammate has to rotate over to help. And once a defense starts rotating, a good offense can pick it apart.

For Michigan, defensive help has been a rarity.

“They don’t help a lot,” said Western Michigan head coach Steve Hawkins, whose team recorded just four assists in a Dec. 15 loss to the Wolverines. “When you drive you can usually -- (against other teams) -- kick it out to people. They don’t leave their man. It’s their style, their system. And it’s a good one.”

Dumb fouls, as Yaklich puts it, are not tolerated. Same for a lack of effort. “If you stop in the middle of a play for any reason, you’re going to visit the top of Crisler.” Like careless turnovers on offense, the Wolverines run their arena’s stairs for committing such mistakes in practice.

Communication is taught, encouraged, and enforced. Basketball coaches are fond of telling their players to talk on defense. Too many players don't know what to say.

"If you don't teach the language to your players and then break that down into small, incremental segments -- 'This situation, this is what you say' -- and don't reinforce and teach that language in the moment, it's hard to say 'talk,'" Yaklich said. He was guilty of this as a young high school coach, but no longer.

If Simpson calls "ice" as a ball screen develops, Teske has to know what that means and how he should react.

Players are held accountable for their communication. Yaklich will crank the volume of a practice film and note whose voices stand out, then praise those players. Certain drills promote talking and players can't exit until they've hit a quota. Against Air Force on Dec. 22, Beilein yanked Matthews and Ignas Brazdeikis -- Michigan's two leading scorers and typically reliable defenders -- within the first 75 seconds of the second half after their failure to talk resulted in a layup for the visitors.

Defensive miscues have been rare for the Wolverines this season. They've held all but one of their opponents under their season scoring average.

The ideal defensive possession, in Yaklich's eyes, looks like this: The ball gets reversed from one side of the court to the other and Michigan must defend multiple actions. The shot clock winds down, and the opponent is forced into a difficult 2-point shot. Michigan, of course, contests this shot.

Asked for a recent example, he cites a second-half possession from Thursday's win over Penn State. Michigan's starting five is on the floor. They're moving in sync, as if connected by a string. The Nittany Lions' sets are stifled, and they resort to isolation. Brazdeikis challenges a baseline fadeaway that misses the rim, resulting in a shot clock violation. A clip like that is likely to end up in Michigan's defensive Hall of Fame.

The Wolverines' awareness of opponents' tendencies is no accident. Beilein is known as a film junkie, and yet even he is impressed by how much Yaklich consumes. (Yaklich was a delayed a few minutes for Sunday's interview because he was squeezing in some final preparation on Indiana's post-timeout plays.) It is not uncommon for Beilein to receive a detailed email while he's sleeping. It means Yaklich has watched that day's practice and can't wait to share his list of observations and suggestions.

Beilein has final say over what gets implemented and when, but he doesn't spend as much time on defense as he used to. "It's really been good for me," Beilein said earlier this season. At practice, when offensive and defensive drills are occurring at different baskets simultaneously, Beilein no longer feels compelled to check in on the latter group every time. "I just let him have it," he said, referring to Yaklich.

No matter the opponent, Michigan prioritizes transition and ball-screen defense. Being solid in transition forces teams to score against a set defense as often as possible. As for ball screens, their prevalence in the modern game makes the ability to defend them essential.

Each game plan has tweaks. Michigan's principles remain the same, but maybe one ball-screen coverage is emphasized over another because of the strengths of a particular opponent.

"Part of defense is really simplifying things so your guys know what to do," Yaklich said. In any given game, he wants his players focusing on two or three specific things that fall under one of the more general areas of emphasis.

If there's one player who embodies Yaklich's influence on Michigan, it's sophomore guard Jordan Poole. While Simpson and Matthews came to Michigan with a dedication to defense, Poole did not. He has it now. Poole is "seeing plays a step ahead," Yaklich said, and communicating that information to his teammates on the floor. He's improved his positioning, getting lower in his stance. "He had the length, but he didn't know how to play smart with his length."

And, most importantly, he's adopted the grit necessary to win a one-on-one matchup.

Poole didn't have much of a choice, not with Yaklich on staff. "I wouldn't be surprised if we were going to training table and he said, 'Get in a stance,'" Beilein said.

"He's talking defense all the time."

A fan who didn't know better might watch a game and think Yaklich was Michigan's head coach. He's out of his seat pointing and yelling on nearly every defensive possession. Given the offensive skill in today's game, he knows how much effort is required to get a stop.

And oh, by the way, if the Wolverines do everything right on a defensive possession, contesting a shot and forcing a miss, their work is not done.

They still have to get the rebound.