The Dallas Mavericks needed an elite point guard to compete in the Western Conference. Rajon Rondo was gathering dust on a horrible Boston Celtics team that needed ammunition to rebuild. This trade was the very definition of a no-brainer for both parties.

The deal, finalized Thursday night, brought Rondo and forward Dwight Powell to Dallas in exchange for Brandan Wright, Jae Crowder, Jameer Nelson, a conditional first-round pick in 2015, a second-round pick in 2016 and a $12.9 million trade exception.

Powell is irrelevant to this deal. He’s there to make the salaries work. Wright, Crowder and Nelson are all good players, and the Mavs will miss them — Mavericks owner Mark Cuban called them “amazing players and better people” via his Cyber Dust text app — but the Mavs can replace that lost depth. Losing the draft picks might hurt, but Cuban would rather have veteran players anyway.

No, this was about closing the gap between the Mavs, who entered Thursday night in sixth place in the Western Conference, and the teams lodged in front of them. The only way they were going to do that was to improve their point guard play. The only way they were going to do that was via trade.

Getting Rondo, despite the price, is a coup of the highest order.

The Mavs have scorers. In fact, they have three — Dirk Nowitzki, Monta Ellis and Chandler Parsons. All are capable of scoring 20 points a night. They have one of the game’s most intimidating defensive presences in the middle in Tyson Chandler. He cleans the glass and blocks the shots. What the Mavs needed was a facilitator and defender at point guard, someone who could get the ball in the hands of these scorers and shut down — or at least slow down — guards like Steph Curry, Tony Parker and Chris Paul.

Few distribute the ball better than Rondo. This season he is averaging 10.8 assists per game. For his eight-year career, he’s averaging 8.49 assists per game, which puts him in the top 10 in NBA history. By comparison, the Mavs’ starting point guard this season, Jameer Nelson, is averaging 4.1 assists per game. In fact, combine backup Devin Harris’ numbers (4.0 apg) with Nelson’s, and they don’t quite match Rondo’s.

And still, with Nelson and Harris, the Mavs are the highest-scoring team in the NBA (110.1 points per game). Rondo may just make this offense downright lethal.

Rondo has a reputation as an above-average defender, and he’s actually one of the better rebounders among guards in the NBA despite being only 6-foot-1. He’s averaging 7.5 rebounds per game so far this year. That’s the best single-season average of his career, though up until the trade he was playing for a Celtics team that needed him to do everything. The Mavs won’t need Rondo to venture to the glass nearly as much, opening him up to slash, drive and dish with a little more freedom.

He’s been an All-Star. He’s played on two NBA finals teams. Perhaps best of all, Rondo has played with superstar veterans before. Early in his career, he played with Boston’s Big Three — Kevin Garnett, Ray Allen and Paul Pierce. He knows how to keep players like that happy. No doubt he’ll have no issues getting Nowitzki, Ellis and Parsons the ball right where they want it, after a short transition.

The negatives? There are two. First, has being on such a sorry team in Boston the past couple of years dulled his drive? It’s a pretty wimpy complaint, given Rondo’s career arc, and it underscores the overall positivity of this move.

The second is more important. Rondo is a free agent after this season, which means the Mavs may have given all of this up for a player they’ll have for three-quarters of a season. There is no guarantee that Rondo will return to Dallas after this season. But, based on the reporting preceding the trade, Rondo was at least “open” to the idea of extending his stay in Dallas beyond this season.

That would satisfy Cuban’s long-term objective — providing a roster of players that could help extend Nowitzki’s career and give him one more push for a NBA title. With Rondo on his way to Big D, his mission may finally be accomplished.