But they still occasionally have those nights that remind you: This team still lives and dies with its veteran Big Three.
This was one of those nights. The Celtics entered Monday night's tilt with the Dallas Mavericks 9-0 in Texas since Paul Pierce, Kevin Garnett and Ray Allen came together in 2007. As teammates in Celtic green, they had never lost a road game in Dallas, San Antonio or Houston. The Lone Star State has had a big three of its own over the past decade, with Dirk Nowitzki, Tim Duncan and Yao Ming forming a trinity of basketball gods in Texas, but they were never a match for the Celtics' power trio.
That changed on Monday.
The Celtics fell behind by double digits in the second quarter, largely because their veterans were having an off night on the tail end of a road back-to-back. They were turning the ball over, they were forcing bad shots, and they were taking possessions off on the defensive end. They were down 14 late in the first half, and it was a miracle it wasn't worse.
Then the Celtics clawed back — largely because Pierce, Allen and Garnett combined for 25 points in the third quarter alone, making a game of it when the C's looked lost. It was renewed effort from the veterans that put the Celtics in position to steal one on the road.
Then they let their guard down again. Whatever edge the Celtics showed in the third quarter, it couldn't be sustained the rest of the way.
"I thought we had mental fatigue," coach Doc Rivers said. "That's what I told them at halftime — I said either we're going to be mentally ready to play the second half, or we're not. And we were. We came out great to start the second half. We just couldn't execute down the stretch. We pretty much got the shots we wanted, but they just didn't go in."
Pierce, Allen and Garnett each missed a very makable shot in the final minute and a half. Garnett's, a four-foot jumper with 37 seconds left that would have given the Celtics an 89-87 lead, was the biggest miss of all. Then when Nowitzki connected on a mid-range shot on the other end to put the Mavs in front by that same 89-87 margin, the Celtics couldn't respond. Rondo missed an ugly 3 in the waning seconds, Allen couldn't get off a put-back, and Garnett missed an ugly fadeaway jumper from the corner as the final buzzer went off.
The Celtics' veterans carried them to crunch time, but they couldn't finish the deal. There were fatal miscues on both ends of the floor.
Pierce blamed the defense.
"Definitely this one is a tough one to swallow," the captain said. "Especially looking at the circumstances — even though we got down, we had a lead late in the game. We just didn't execute well defensively down the stretch. When you leave a couple guys open with the game on the line, that hurts."
Rivers countered with his case against a Celtic offense that went scoreless in the game's final 1:58.
"You put yourself in a hole in the first half, and you're exhausted trying to get back," the coach said. "We missed some good shots down the stretch. Paul had two good looks at the basket, and Kevin had a layup, but everything was short-armed and short-rimmed. That happens."
It happens to a lot of teams. But historically, it hasn't happened to these Celtics — not since the Big Three came together, and not in Texas where these C's have been unbeatable for years. On Monday night, this team discovered its mortality.