After starting Wednesday off by sounding the alarm on the Knicks' teetering season, Anthony went scoreless in the fourth quarter and ended his day in pure frustration after the 76ers shocked the Knicks 98-97 at the buzzer.
Anthony scored a game-high 28 points but watched T.J. McConnell drill the latest game winner against the Knicks over him to set off a delirious Sixers celebration. For the Knicks, it was the most demoralizing loss of the season.
A deflated and exasperated Anthony could only watch as the Knicks lost for the ninth time in 10 games, after blowing a 10-point lead in the final 2:29. Over the past 20 seasons, the Knicks had been 372-0 with a 10-point lead in the final three minutes of the fourth quarter.
It was also the second time an opponent had hit a buzzer-beater to defeat the Knicks in the past five games, as McConnell joined Milwaukee's Giannis Antetokounmpo, who drilled a winner at Madison Square Garden last week.
"Very, very disappointing," said a dejected Anthony after the latest loss. "... I don't even know what to say about this one."
"We should tell ourselves that it's unacceptable," Anthony added later, when asked if this was an unacceptable loss. "We were winning this game coming down the stretch. We were winning with 20-something seconds left. We came up short. So it should be unacceptable to all of us."
Anthony, who was trying to get the Knicks back on track after he was ejected for the third time this season during the second half of a 110-96 loss at home to the New Orleans Pelicans on Monday, scored all 28 of his points in the first three quarters Wednesday and capped the third with a 3-pointer.
But Derrick Rose -- who returned to the Knicks after missing Monday's loss without giving the team any word for hours, explaining later that he left for Chicago to see his mother amid a family issue -- had the hot hand in the fourth against the Sixers. Rose scored eight of his 25 points and made all four of his shots in the fourth.
Anthony went 0-for-3 in the fourth quarter and missed a 3-pointer with 1:03 left and the defenseless Knicks clinging to a three-point lead. After Philadelphia scored, Rose answered with a difficult reverse layup over Joel Embiid to keep the Knicks' lead at three with 34.5 seconds remaining.
The Sixers scored again to cut the deficit to one, and Knicks coach Jeff Hornacek called on Rose. Anthony came over to screen for Rose, who drove baseline before drawing the defense and passing out to Brandon Jennings at the top of the key. Jennings found an open Kristaps Porzingis on the right baseline, but the second-year forward missed a 3-pointer badly.
The ball was tipped away from the basket, and the Sixers grabbed the loose rebound, leading to a frantic scramble downcourt. McConnell got the ball on the left baseline, and Anthony came over to stop the Sixers' point guard from driving to the hoop. McConnell made contact with Anthony with his right hand before stepping back and knocking down the winning shot.
"There was so much going on. I don't want to give you an answer that is wrong," Anthony said when asked about the final sequence. "I can't recall. I have to go back and look at it."
During the morning shootaround Wednesday, Anthony said he didn't think the sinking Knicks (17-22) had reached the low point yet or were in a dire situation. But the Knicks were four games above .500 in December. Now they are slipping in the standings.
Anthony warned that if the Knicks don't start playing better soon, the season could spiral.
"I think now is just a time that everybody can just exhale a little bit and kind of relax," Anthony said after the shootaround. "It was a little tense around here the last couple of days. You can't play basketball like that. We all need to just relax and focus and put everything else behind us."
"I've seen it for the past couple of years," Anthony later added of his concern. "But I still don't want to say [I'm] frustrated. It's not worrisome. I've seen it before. I've seen this happen before. I've seen it go downhill quickly. I don't think this is the situation. But we have to turn this thing around quickly."
The Knicks limp back to Madison Square Garden, where they hope to stop the bleeding against the Chicago Bulls on Thursday.
"There was a lot of lessons," Anthony said of the defeat in Philly. "I can't give you one lesson right now. There's a lot of lessons we can learn from this."
Information from ESPN's Ian Begley and ESPN Stats & Information was used in this report.