Dereck Lively II and the Dallas Mavs are now done with 2023 NBA Summer League, and we’ve learned some things. The former Duke big man showed off many of the skills that made him the No. 12 pick in the NBA Draft. However, he also showed his biggest weakness when it comes to setting screens, which he will do a lot at the next level.

The Mavs' biggest concern about Dereck Lively II after 2023 NBA Summer League is his screen-setting

On balance, the Dereck Lively II Mavs NBA Summer League experience was an incredibly positive one.

Dallas took a chance on Lively with the No. 12 pick despite his struggles in college. The 7-foot-1 center was the No. 1 high school recruit in the country in 2022 but disappointed at Duke as his less-heralded classmates — Kyle Filipowski and Mark Mitchell — outperformed him last season.

Despite that, the Mavs saw a player in Lively who can do a lot of the things they will need next season with Luka Doncic and Kyrie Irving in the fold. He is an incredible athlete, a plus rim protector, a good rebounder, an excellent screen-and-roll rim runner, and has some decent shooting touch for a player his size.

And in the five Mavs NBA Summer League games he played in, Lively showed off a lot of his skills.

The numbers over these five games were solid. He averaged 8.4 points, 8.0 rebounds, and his team was a +7 with him on the court. He also shot 68% from the field and recorded three blocks. If you project these numbers out to what will happen when he’s playing full NBA games with the likes of Doncic and Irving, Lively has the potential to be a 15-and-10 guy right out of the gates and a 20-and-10 big man down the road.

Watching Mavs NBA Summer League games is the only true way to get an appreciation for what Lively can do for the team in the regular season, though.

He may have only recorded three blocks, but his presence in the middle of the floor went way beyond that. Lively altered shots, forced kick-outs, and generally discouraged players from coming into the paint when he was there.

Offensively, he has some monster dunks on the break and as a result of screen-and-rolls. In the team’s final NBA Summer League Game — a 101-80 win over the Atlanta Hawks — Lively was a perfect 5-of-5 from the field while scoring his 10 points and pulling down six boards. When you think of what could come of having Luka Doncic or Kyrie Irving as the ball-handler on these players during Lively’s rookie season, the prospects are tantalizing.

So, after the Mavs NBA Summer League run, it looks like Lively will be solid on defense and an excellent finisher at the rim. It’s getting to that last part which is Dallas’ lingering concern about Lively leaving Las Vegas.

The biggest concern about Dereck Lively II for the Mavs is his screen setting. This may seem a little nitpicky, but it is going to be a huge part of his game, and setting weak screens will not only hamper his offensive game but the entire team's.

Lively is 7-foot-1 and 230 pounds. He still needs to add weight, muscle, and strength to bang with the big boys in the NBA. At Summer League the big man didn’t plant his feet set strong screens for his guards to work around. He too often threw his hip out to stop a passing defender, and that led to a lot of fouls.

In Vegas, where each player has 10 fouls, it wasn’t a huge problem. Come the regular season, though, with just six fouls to give each night, setting illegal screens will land the center on the bench quickly.

Also, if opposing guards are easily able to fight over or around Lively’s screens and stick to Doncic or Irving, the rookie’s presence on offense will be a net negative.

The good news is that while this is not a small problem, there is time to fix it, and it is easily fixable. Lively needs to bulk up a bit without losing his athleticism. And most rookies, when exposed to an NBA training regimen, are able to do this when they get to the league.

As far as technique goes, one of the real positives is that Lively is already working with former Mavs big man and 2011 NBA champion Tyson Chandler. That is the archetype of who Lively can become in the NBA, and there are few better screen-setters in league history than the 18-year vet.

Chandler is ultimately one of the pieces who helped deliver Dirk Nowitzki a title in Big D, and Lively could be that same type of piece for Luka Doncic.