The Cleveland Cavaliers may be in serious trouble, and Isaiah Thomas could be at the center of it.

After Monday’s loss to the Golden State Warriors, several of the Cavaliers players were in foul moods in the locker room, appearing to have no answers for what has gone on with them over the past several games. Many topics came up, including that of Thomas’s defense as compared to Kyrie Irving, per Joe Vardon of Cleveland.com.

Multiple marquee Cleveland players spoke without attribution to cleveland.com, ESPN and The Athletic after the loss to the Warriors, and league sources separately spoke to cleveland.com to describe a sullen and dour atmosphere on a team that a few short weeks ago was toasting in Napa, Calif.

“Rotations are awful. IT (Isaiah Thomas) is so much worse than Kyrie (Irving) defensively it’s insane,” said a league source. “There is not a great feeling anywhere. They need to limp into the All-Star break and get away from each other.”

That does not sound good. The Cavaliers have lost eight of their last 10 games, including two to the Warriors. There is clearly something going on with the team as a whole.

In terms of Thomas’ defense, the source may be right. Thomas was not brought to the Cavaliers to be a defender. He was brought to put the orange ball through the red ring.

At one point when he was with the Celtics, it was reported that he may have been the worse defensive player in the NBA. But Thomas just joined the team after returning from injury, so there’s still time for him to shed that image.

But the Cavaliers as a whole need to figure something out and quickly.