2. Marcus Morris
Marcus Morris played with Kyrie Irving throughout their whole tenure in Boston together from 2017 to 2019. In the same vein as O'Neale, Morris is also on an expiring deal next year and is set to make a hedge over $17 million this upcoming season.
After Morris' brother, Markieff re-signed with Dallas on a partially guaranteed deal just days ago, the reading is in the tea leaves for the Mavericks to go full UNO-reverse card mode with Marcus Morris.
Adding the second Morris twin to the Mavericks' roster would be a little odd given Luka Doncic had some playoff beef with Marcus Morris in the NBA's COVID-19 bubble in Orlando a few years ago, but the Mavericks would assuredly have a tough set of guys to defend Luka at their disposal at the very least.
Furthermore, Marcus is a lot more dynamic on offense than Markieff, as he averaged over 15 points a game just two seasons ago. Marcus has a reliable post-game and can be a stop-gap isolation scorer when the Mavericks offense stalls out. He's gotten a little bit slower defending on the perimeter just like his twin Markieff, but he's still very physical on defense and a great shooter at the age of 34.
The Mavericks would have an abundance of tough-minded veterans on their roster if they added Morris, and so long as there were no locker-room issues sparked by either of the twins, the Mavericks would have one of the grittier organizations in the NBA.
It's a bit of a wildcard to add Morris, given his past beef with Luka Doncic, but the veteran would bolster the Mavericks' wing depth to another level if things worked out. He wouldn't improve the Mavericks as much as the next former teammate of Kyrie Irving on this list, though.