Muffet McGraw has been worried all season about Notre Dame’s defense. When the Fighting Irish beat Bethune-Cookman in the first round of the NCAA women’s basketball tournament, McGraw said in postgame interviews that her team had “a long way to go to be a good defensive team.” This was after Notre Dame conceded only 50 points and won the game by 42.Fast-forward a couple of weeks, and McGraw’s team has now reached the Final Four for a ninth time. Next up is a bitter rival — and the most decorated team in the sport’s history — in the Connecticut Huskies. It’s safe to assume which aspect of Notre Dame’s game concerns McGraw the most ahead of this epic rematch of last year’s semifinal.After all, Notre Dame is a juggernaut on offense. The Irish are first in the nation in points per game and third in offensive efficiency, according to HerHoopStats.com — trailing only Oregon and Mississippi State. Both stats are on par with what the team posted last season en route to the national title.But despite McGraw’s concerns, Notre Dame has come a long way toward becoming a good defensive team. It’s just not on the same level as the impeccable execution Notre Dame displays on the offensive side of the ball. Last season, Notre Dame ranked 150th in defensive efficiency. For comparison with recent champions, South Carolina finished 18th in 2016-17, while UConn’s 2015-16 team finished first — in fact, the Huskies finished first in all four of Breanna Stewart’s title-winning seasons. (Not a coincidence.)Typically, championship teams play far more effective defense than the Irish did last season. So far in 2018-19, though, they’ve bridged that gap significantly. Though they are allowing 64.2 points per game, 153rd in the country, that number fails to account for Notre Dame’s pace. In defensive efficiency, they are up to 52nd in the country. Notre Dame’s defense has made big stridesHow the Final Four teams have changed from a year ago in terms of their efficiency on offense and defense Notre Dame114.2117.5+3.391.886.1+5.7 Source: Her Hoop Stats Oregon117.8121.9+18.104.22.168-1.4 Team2017-182018-19Diff.2017-182018-19Diff. UConn122.2116.8-5.473.779.6-5.9 Baylor117.4113.1-4.377.276.4+0.8 Points Per 100 PossessionsOpp. Points Per 100 Possessions Notre Dame star Arike Ogunbowale is a big part of that, though she’s by no means alone. The whole team had to pitch in to guard Texas A&M star Chennedy Carter in the Sweet 16 on Saturday, and while Carter did manage to score 35 points, this number is deceiving: It took Carter 34 shots to do it. Ogunbowale scored 34 in the game but did so on just 25 shots.“I think we got stops when it mattered,” Ogunbowale said after the Texas A&M game. “Fourth quarter we held [Carter], we got stops. And like I say, we got stops when it mattered. So that’s all that matters.”This has been the case for much of the season. Notre Dame is allowing 0.73 points per possession this season overall, per Synergy Sports. But after timeouts, that number drops to 0.59, good for sixth in the country. So when McGraw and company have a chance to set up their defense, the Irish essentially become as effective as anyone, with that number besting everyone else still left in the NCAA field.So how do they do it? A combination of forcing turnovers, closing out on perimeter shooters and an elevated dose of protecting the rim.The Notre Dame steal percentage is up from last season, 12.0 percent this year from 11.1 percent a year ago. Much of that improvement comes from Ogunbowale herself, whose steal rate jumped from 2.3 to 3.2 percent. All five starters, however, have steal rates north of 2 percent, reflecting an ability to get into passing lanes, and those live-ball turnovers are immensely valuable for a Notre Dame team that scores at a rate of 1.12 points per possession in transition.The biggest change, though, is the element of rim protection provided by Brianna Turner after the Notre Dame center missed last season with an injury. No Notre Dame starter last season topped Jessica Shepard’s 2.3 block percentage. But this year, Turner checks in at 9.2 percent, and as a team, Notre Dame is at 11.5 percent. That’s 38th in the country, up from 225th in Division I last year.But while most attention goes to Turner’s blocks — a particular aesthetic favorite of McGraw when she watches her team — there are improvements by other players that have made a difference as well.Take Shepard’s ability to end possessions by simply anchoring herself in the right spot off of misses by opponents. Her improved strength and agility this season has led to a significant jump in her defensive rebounding percentage, from 17.1 percent last year to 20.5 percent this season.“Jessica is such a phenomenal player inside and out,” Turner said of her teammate when talking to reporters in Chicago on Sunday. “She’s the strongest player I’ve ever played against or with, so that just speaks for itself. Her ability to like chase down rebounds and just offensively, as well, just her strength is really one of her great assets.”Then there’s Marina Mabrey, known primarily for shooting threes and taking over at point guard last season out of necessity. But the versatile Mabrey is also a standout on defense. Already strong last season at 0.676 points per possession allowed, per Synergy, she’s dropped that number all the way to 0.625 in 2018-19, 45th in the country among 713 eligible Division I players with a minimum of 200 possessions. This stems from her ability to defend spot-up shooters. Her allowed points per possessions on these plays is down to .587 from 0.855 a year ago. The result is a Notre Dame team that allowed opponents to shoot 34.5 percent from three last year, 302nd in the nation, but now is giving up just 28.6 percent to opponents beyond the arc this year, 33rd best in the country.To be sure, there are still gaps in the Notre Dame defense. As McGraw noted last weekend, the team’s offense is what holds the key to its defense, an inside-out formulation compared with most teams.“We do like to run,” McGraw said. “We’re a transition-type team. I think our offense feeds our defense, which is kind of the opposite of the way it’s supposed to go.”It’s true: While the Irish are among the nation’s leaders in offensive efficiency both in the halfcourt and in transition, they have a far more effective defense in the halfcourt set (55th in the nation, per Synergy) than in transition (197th). Put simply, the best way for Notre Dame to defend is to make baskets and keep opponents from running.And while Notre Dame has every chance to repeat, don’t think of this 2018-19 Irish team as a clone of last year’s champion. Check out our latest March Madness predictions.