CLEVELAND, Ohio -- Tyronn Lue's recent starting lineup change has given Kyrie Irving a substantial new responsibility: defending the point guard.

This might seem like an obvious assignment given Irving's position, but over the last few months, while J.R. Smith recovered from a thumb injury, DeAndre Liggins or Iman Shumpert took that challenge, an attempt to cut off "the head of the snake." It was also part of a big-picture plan to keep Irving from getting worn down in the regular season, keep him from having to fight through a plethora of on-ball screens.

With J.R. Smith back in the starting lineup, a move Lue made prior to Wednesday's loss against the Denver Nuggets -- the defeat that led to both Lue and LeBron James questioning the team's toughness -- Irving is back to defending on the ball.

"It's a lot of pressure to have him be one of our scorers and then having to guard the best player on the other team," Lue said. "It's tough, but it's part of the NBA. Every night he's going to have a tough matchup, along with those (other point guards). They've got a tough matchup when they have to guard him so just have to step up and do it."

The results haven't been encouraging.

On Friday night, Hornets point guard Kemba Walker shredded Cleveland's feeble defense. He blew past Irving and others, either getting into the paint repeatedly or creating enough space to pour in jumpers from the outside. He tallied 28 points on 10-of-20 from the field, including 5-of-10 from 3-point range. He also added five assists, as Charlotte outscored the Cavaliers by 12 points with Walker on the floor.

John Wall became the latest to exploit Irving's defensive deficiencies Saturday night, leading an assault in which Irving has so often been on the other end.

A blur on the court, Wall scored a team-high 37 points on 14-of-21 from the field, including 2-of-2 from beyond the arc. With a determined look in his eye early, out to avenge Washington's recent overtime loss against the champs, Wall attacked relentlessly. He scored 18 points in the first quarter, making all eight of his shot attempts, as the Wizards scored 40 points, the most the Cavs have sacrificed in the first period all season.

"Last time we played, Brad (Beal) got it going so we started out being very aggressive on his pick-and-rolls and John was coming off and he started off with a midrange jump shot in transition and when he gets a good feel, he starts pushing it every time and an even better feel, he starts hitting 3-point shots," Irving said. "When he starts playing like that at a high level, he's tough to maintain and he showed signs of that. Going forward, we'll be better prepared."

The last two point guards to face the Cavs have combined for 65 points on 24-of-41 (58 percent) shooting.

Lue spoke about having a secret plan to fix the defense, but even admitted he's not confident things will change. Irving will be a big part of that.

With Smith in the starting lineup, Irving needs to be much better at the point of attack. Lue said putting Smith on the point guard is "not something we like to do." That puts the pressure on Irving. Given his reputation as a subpar defender, he will be in the opponent's crosshairs.

"It doesn't change anything," Irving said. "Offensively and defensively, it's the same mindset. Our rules that we stick to with whatever point guard that we're playing against, we just got to stick to our defensive gameplan if those guys are making shots and we go into a blitz action and try to stop them a little bit. But when they're hitting outside shots, hitting their midrange shots, they're tough to contain. On the flipside, I still got to stay aggressive offensively and get my teammates involved."

The Cavs have used simplistic defensive strategies that haven't worked. The Wizards (127 points) became the fifth team this month to score at least 120 points, as the Cavs are now statistically the second-worst defensive team since the All-Star break.

Shuffling rotations and incorporating new pieces has created challenges. There's a lack of connectivity and communication -- both of which have led to breakdowns. But there's also a dearth of quality individual defenders and Wall took advantage.

So what's the answer? What's the best way to fix the problem? Waiting for the postseason seems to be the only response the Cavs have at the moment.

"We just got to figure it out and continue to see what fits our group, see what fits our lineup, see what fits our team as a whole and what's going to give us the best shot to win each and every game," James said. "Like I said, you can't base last year on this year. This year is different. Every year is different, so I think our coaching staff will figure that out for us."

In the playoffs, the Cavs will be able to lock into one opponent. But Wall could be coming again. So, too, could Boston's Isaiah Thomas, Toronto's Kyle Lowry or any number of talented lead guards. Irving better be ready for the challenge. With Shumpert coming off the bench, they're all Irving's responsibility now.