Those are facts. Right here, I'm going to try to cover all the major facts about those last few seconds in the AT&T Center before giving my opinion on what happened.
Manu Ginobili took the foul the Spurs had to give with 5.6 seconds left on the clock.
Vince had hit two of his last three shots: a made three with 1:54 left (wide open from the corner), a missed three with 3:34, and a made layup with 4:01 (very difficult scoop shot, I thought it should have been a foul too).
Mayo inbounded the ball to Carter, while Brandan Wright came from the elbow to set a pick on Kawhi Leonard. Wright's man, Splitter, and Leonard switch with around 3.5 seconds left on the clock.
Carter takes a dribble left, crosses over right, and shoots a three with 2.5 seconds on the clock. Splitter contested well, forcing Carter to fade on the shot.
The shot hit the side of the rim at 0.8 and bounced out.
According to NBA.com, when the Mavericks up or down by 3 points with less than 10 seconds on the clock, Carter is 2-8 and Dirk is 1-1. Via Bryan Gutierrez, two of those Carter shot attempts came when Dirk was still out.
Carter has not played too well in the clutch this season. He's just 10-27 on shots taken with 5 minutes left in the game with the Mavericks +/- 5 points. (again via NBA.com)
In that same situation, Dirk is 13-24 (54%) although just 11-16 (69%) shooting free throws. He's played 50 minutes in that clutch situation compared to Carter's 85.
Carlisle: "We gave ourselves a chance. I'm disappointed the last one didn't go down, but Vince created a pretty good look."
Carlisle: "We were trying to get a clean open shot, the cleanest shot that we could get. Vince was the one guy we have that can create that separation, so it was either going to be a roll to Wright or he would take that shot himself. It's very difficult in that situation, with five seconds left, to get the ball to Dirk in a position where he can really do something with it. They're going to be laying all over him."
Dirk: "They had a foul to give down the stretch and they took it early, we still had 6 seconds left to get a good look in. I was kind of in [Carter's] way, I don't think I necessarily liked the play call. We knew they were switching, I probably should have got out and let him create with more room up there."
Dirk: "It was just a pick and roll play, and get the ball to Vince is great, but there was really no room to go with me standing right there on his left. I probably should have cut out or did something to give him more room to drive; this way, he only had the three."
5.6 seconds is not enough time to set up Dirk in a spot he likes on the floor and expect a quality look unless the Mavericks were able to get a direct pass off the inbounds to him. Like Carlisle said, the Spurs would be "laying all over him" and almost no chance of that working unless Dirk catches outside the three point line.
It has happened before, such as this one right here, but Pop is too smart to let that play happen. Several years ago, maybe it'd be wise to take the chance and let Dirk get the ball far from the basket, but I'm not sure Dirk moves well enough that there would be total confidence in him getting a quality look in that amount of time. Plus, Pop is sure to send a double if that were to happen.
Looking at some more of Dirk's game winners, it really works best if he has 10-12 seconds on the clock. This one triggered at 12 seconds, as well as this one. The layup against Boston last year also triggered at 12 seconds. That's a solid amount of time that Carlisle and the Mavs simply didn't have.
I don't think Dirk should have taken that last shot. He should have been used as a total decoy, rather than the "maybe could bail the play out if Carter had to pass" option that was very unlikely to be used. Like he said post-game, the best option was for him to cut out of the play.
As for Carter, he was in a tough situation. I would rather see him put the ball on the floor and try to pull up from 18 feet, but the spacing wasn't perfect. 2.5 seconds is when he started the release, but it was 2.0 by the time left his hand. Considering coaches always say one dribble equates to one second, he really only could make a single dribble unless he wanted to come very, very close to releasing the shot too late.
I won't stop anyone from blaming Carter if they see fit, or Carlisle for not making more of an effort of getting Dirk the ball, but to me, I think that rimmed out three pointer was about as good as the Mavericks could have done in that situation.