At the start of the third quarter against the Clippers on Tuesday night, the Mavericks got a stop and ran down the court for their first offensive possession of the second half.

Dennis Smith Jr. brought it up and passed it to Wesley Matthews. From there, neither Smith or Luka Doncic touched the ball again. Instead, Harrison Barnes ran a pick and roll. The results were predictable.

On a team with the most dynamic offensive rookie since LeBron James and a 21-year-old point guard with rocket-boosted hops, the Mavericks instead opened their second half — a set that was probably discussed in the locker room during halftime — by pinging the ball between the three worst players on the roster with the ball in the their hands.

That’s why the talk of whether Smith and Doncic can coexist always seemed rushed and premature. There were always going to be bumps in the road for Smith to basically learn a new position after having free reign during his rookie season. Yet that has somehow spiraled into trade talks and rumors. And throughout all that, the problem with the Mavericks isn’t what to do with the only two young cornerstones on the roster — it is the two role players that cannot function together.

Ball movement is a big problem

Barnes and Matthews aren’t bad players and they’ve both played in highly regarded offenses — Matthews with Terry Stotts in Portland and Barnes with the 73-win Warriors team. So it’s not like these two can’t be part of a high-performing offense, it’s just that when they’re mixed together, toxic results happen.

Both Barnes and Matthews are best suited as catch and shoot third or fourth options. Guys who can spread the floor, hit open shots and make very basic reads when necessary. They’re limited with their offensive games, meaning you don’t want these guys running an offense. The problem comes when they’re together and it limits the offensive ceiling of whatever lineup they’re in for the Mavericks. Dallas doesn’t need Barnes and Matthews to be big assist guys, but they need them to just move the ball and that’s not happening when they’re together.

Consider this — Barnes averages 5.5 drives per game, according to NBA.com/stats. On those 5.5 drives, he’s passing it just 17.9 percent of the time. That is the worst mark on the team for anyone averaging 20 minutes per game. It’s also one of the worst marks in the league. And Barnes doesn’t even justify those black-hole drives with shot making — he’s shooting just above 40 percent on those drives. Of all the players in the NBA averaging at least five drives per game, Barnes has the third-lowest pass percentage on drives.

Matthews is a bit better, passing on 30.6 percent of his drives. But that’s still not a terrific number, and combined with Barnes, the Mavericks’ offense slows to an absolute crawl with both of them on the court. Barnes and Matthews have played 926 minutes together entering Friday night’s game against the Pistons, the sixth-most on the team for a two man duo, and they have a minus-3.6 net rating. At 1.1 assists per game for Barnes and 2.4 for Matthews, the Mavs just get zero ball movement when those two are on the floor. It’s part of the reason the Mavs starting lineup is one of the worst in the NBA.

Luka and Dennis need the ball

This can’t happen on a team that has put their draft stock in players like Smith and Doncic. If those two are supposed to be the future, it’s impossible to get a good read on how they can play together when Barnes and Matthews are barreling into the lane or hoisting ill-advised jumpers. Smith and Doncic haven’t been good, to be fair, with a minus-4.6 net rating together, but look how much better the duo is when they’re only playing with one of Matthews or Barnes and not both.

When Luka Doncic and Dennis Smith Jr. are ON COURT Description MIN OFFRTG DEFRTG NETRTG Description MIN OFFRTG DEFRTG NETRTG Harrison Barnes is ON COURT 558 99.2 104 -4.9 Harrison Barnes is OFF COURT 129 105.1 109.7 -4.5 Wesley Matthews is ON COURT 457 101.7 107.6 -5.9 Wesley Matthews is OFF COURT 230 96 98.2 -2.2 Dorian Finney-Smith is ON COURT 240 104.9 105.1 -0.2 Dorian Finney-Smith is OFF COURT 447 97.2 104.1 -6.8

Dorian Finney-Smith is a significantly worse shooter than both Barnes and Matthews. The reason Smith and Doncic play better with him is because they get the ball back and can actually do some work instead of watching a meandering post-up or drive. Finney-Smith passes on 43.7 percent of his drives. Barnes is third on the team in usage, Matthews is sixth — Finney-Smith is 14th with a 12.6 usage rating. To the point, Finney-Smith moves the ball and Matthews and Barnes don’t. What he gives up in consistent shooting he gives back by not letting the ball stick and making sure the Mavericks best playmakers are allowed to make plays.

When Barnes and Matthews share the floor, Rick Carlisle has a penchant for stopping whatever flow the Mavericks have and calling plays for his veterans. Barnes and Matthews lead the Mavs in post-ups per game and while Barnes has been anemic on his (40.7 percent shooting from the field on those post-ups), Matthews is actually pretty good. He’s hitting 54.2 percent on his post-ups and that’s useful for when an offense can bog down. The problem is it seems the Mavericks offense only truly bogs down when they call these post-ups in the first place. They’re a band-aid the Mavericks need to rip off now that they have two young playmakers that need touches and reps.

Here’s a fun fact: Did you know that Smith and Doncic have yet to run a pick and roll with Doncic as the screener this season? It would be cool if the Mavericks started experimenting with those two instead of pounding a square peg into a round hole every other possession when Barnes and Matthews are on the floor.

All of this isn’t even mentioning that the fifth player in the starting lineup, DeAndre Jordan, is leading the team in turnover rate despite his role as a rim-running center. So that’s three players that when they touch the ball outside of obvious scoring scenarios the most likely outcome is a turnover or missed shot. It’s really hard to build a successful starting group when three of the players do that. This doesn’t mean Barnes needs to act like Luka and sling the ball over the floor — it just means he has to move the ball from side to side and not stall things with a drive against two or more defenders.

The Mavs even out a bit when they replace one of Barnes or Matthews with Finney-Smith or Kleber, as both of those guys have no problem sharing the ball. In a way, Barnes and Matthews already feel like relics of the Mavericks rebuilding teams of the prior two seasons. They just needed dudes to soak up possessions and shots because there wasn’t anyone else to do it. Now there are two guys that can do it and they need as many touches as they can handle. There’s a definite downside to surrounding Doncic and Smith with a bunch of low-usage ball movers and that’s when teams wise up and shift their defenses toward them That’s why it’s so important for Smith to stick around, so Doncic can have a proper release valve to attach scattered defenses after double-teams. You can conceive a scenario where Doncic and Smith get overwhelmed carrying the offense while guys like Finney-Smith and Kleber are left wide open and forced to make plays. The thing is, it’s obvious that Barnes and Matthews aren’t the guys to make those plays.

Smith and Doncic could still work well together! Or not!

So who knows, maybe Smith and Doncic really can’t work together. We don’t really know and that’s the key — we don’t know! We know who Barnes is and we know who Matthews is. Against the Pistons on Friday night, Doncic had a 32-8-8 line with Smith complimenting him with a 19-2-5 line. Barnes went 2-for-10 from the field with nine points and Matthews had zero points in 15 minutes. In place of Matthews normal big minutes, Finney-Smith got 18, Kleber got 22 and Dwight Powell got 21 — all guys that have no problem moving the ball and not standing still without it.

We’ve got two and a half seasons of data that show the Mavericks can’t be a good team with Barnes and Matthews as their two big-minute players. The Mavs have consistently played much better when those two guys haven’t been on the floor. Now it’s time for Dallas to figure out if the young duo they just drafted can be the answer.