It wasn't the rebounding or the poor shooting. It wasn't the points in the paint, and it wasn't the foul trouble.
No, the New York Knicks' Game 1 loss to the Indiana Pacers boiled down to something that had nothing to do with statistics or matchups.
"You chuck out the X’s and O’s, they just flat-out played harder than we did," Knicks forward Carmelo Anthony said. "They outplayed us, outworked us. Nothing else needs to be said."
That's a pretty damning indictment of a veteran team playing in the postseason's second round for the first time in 13 years.
"It's the playoffs," J.R. Smith said. "You can't be outplayed or outhustled."
But that's exactly what happened on Sunday afternoon. The Pacers outrebounded the Knicks by 14, outscored them on second-chance points, 20-10, and had 14 more points in the paint.
"At this level you have to be ready," Jason Kidd said, "and we just weren’t."
They also weren't helped much by their leading scorer.
Anthony struggled with his shot all afternoon against the physical Pacers' defense. He finished the game 10-for-28 with a game-high 27 points and had just 10 points at halftime.
His shot has been off for the Knicks' past four games. He is just 35-for-110 in that span.
Against the Pacers, Anthony was matched up against David West, one of the top true power forwards in the Eastern Conference. Anthony is 15 pounds lighter than West and one inch shorter. The physical toll of guarding him seemed to wear on Anthony, playing through an injured left shoulder. Anthony did not use that as an excuse after the game.
"They beat us on the glass, the hustle plays and they outworked us," Anthony said. "It had nothing to do with them being more physical."
But the physical play left Anthony in foul trouble early on. He picked up his fourth with 7:48 to play in the third quarter and had to head to the bench.
The Pacers outscored the Knicks by 10 the rest of the quarter, taking a 16-point lead into the fourth.
"The foul trouble put a dent in the game plan today," Anthony said.
Knicks coach Mike Woodson, though, said Anthony's foul trouble "wasn't the difference" in the game.
The difference was much simpler -- and more alarming -- than that.
"I thought they played harder than our team tonight," the coach said. "That was the difference."
You can follow Ian Begley on Twitter.