At this late stage of the season, every defeat and every injury seems twice as perilous to the Knicks’ playoff hopes. Marbury said his shoulder was fine, and that he simply had a stinger. Frye has a corneal abrasion and blurred vision, however, and his status is uncertain.  The Knicks are already missing Jamal Crawford, David Lee and Quentin Richardson, leaving the rotation dangerously thin.  “I was just trying to figure out who I was going to put in and how we were going to play,” Thomas said. “We will recover.”  The Knicks stayed with the Mavericks through the first half but fell apart in the third quarter and trailed by double digits for the entire final period. The Mavericks had the superior talent, but it was the Knicks’ uncharacteristic errors that doomed them.  Marbury went 2 for 10 from the field, missing layups and 3-pointers. But all of the Knicks seemed to miss near the rim at some point. In the critical early minutes of the second half, Nowitzki stripped Curry and blocked a Renaldo Balkman dunk attempt. The Knicks also sabotaged themselves with a 24-second violation, two missed free throws by Curry, a missed fast-break layup by Nate Robinson and a bobbled ball at midcourt by Jeffries.  “We had a lot of errors in the second half — free throws, easy layups, fast-break turnovers,” Marbury said. “It’s just something that happened.”  Marbury sat out the final 5 minutes 21 seconds, holding his left arm on the bench. But the Knicks were already down by 13 points when he checked out for good. Marbury had lost the ball as he dribbled into the paint, then fell to the floor, where Howard fell on his shoulder.  Last season, Marbury missed 11 games after spraining the same shoulder, but he said this injury was not serious.  Frye had his eye poked by the Mavericks’ Devin Harris early in the third quarter and did not return. Frye, who had just posted consecutive 20-point games, spent most of the second half in the locker room.  The Knicks lost despite a resurgence from Curry, who had his first 20-point game since March 2. Despite missing the morning shoot-around with a stiff back, and having a terrible night at the foul line (4 for 12), Curry finished with 22 points and 12 rebounds. He was the only starter to score in double figures. Marbury and Steve Francis combined for just 14 points and 8 assists.  Jeffries drew the impossible assignment of containing Nowitzki. When halftime came and Nowitzki had only 11 points, it seemed like a minor accomplishment.  A day earlier, Thomas practically conceded the game to Nowitzki, with a rare hyperbolic flourish. He called the Knicks “helpless” and “defenseless” to guard Nowitzki and said there was only one solution: “Pray.”  Guarding the paint might have helped too. The Mavericks had 20 points in the paint in the first quarter alone. They scored 11 of their first 18 field goals on layups and dunks.  “You can’t really use this game as a barometer game,” Marbury said, “because those guys are a really good team, they’ve been playing with each other for a long time. We’ve just got to continue to try to get better and try to become a team like them. When those guys are on the court, they always seem like they’re on the same page at all times.”  Quentin Richardson missed his third straight game because of a sore lower back, and the Knicks gave no indication whether he was expected back soon. Richardson has insisted that there is nothing structurally wrong, but he has missed 14 games — and most of two others — because of back problems. ... Mark Cuban is renowned as a risk-taker, so it should perhaps come as no surprise that he endorsed the Knicks’ much-criticized decision to extend Isiah Thomas’s contract. “It’s not just about, ‘Should he stay or should he go?’ It’s ‘Who’s next?’ ” said Cuban, the Mavericks’ owner. “Who’s next isn’t always who’s better. Working with a guy and letting him develop and letting him get to a point where he can succeed, and giving him the tools he needs, in the N.B.A., is a far better strategy than just saying, ‘O.K., next, next, next.’ “ Cuban praised the Knicks’ progress. He said their better chemistry and camaraderie was evident. “As an owner, I see that that’s a cultural change. That’s going from a place where people didn’t want to be, where there was so much drama, and no one wanted to be, to a scenario where people want to be here and are glad to be here. That’s huge.” ... Cuban and Thomas overlapped for one year at Indiana University, but Cuban said they never met. “He was the stud on campus,” Cuban said. “I was just a freshman alcoholic.” Cuban later clarified that remark: He was a senior when Thomas was a freshman.  A version of this article appears in print on , on Page D1 of the New York edition with the headline: Dallas Leaves Knicks Battered and Bruised. Order Reprints| Today's Paper|Subscribe
There were chants of “M.V.P.” Tuesday night at Madison Square Garden as Dirk Nowitzki’s campaign picked up steam, leading the Dallas Mavericks to a rout of the Knicks.