Why the Heat do this: Duncan Robinson has lost his spot in the starting lineup, with Herro winning 6th man of the year and the surprising emerge of Max Strus, it seems very unlikely the Duncan returns to Miami the next year. They replace Robinson with THJ, yes, maybe another catch-and-shoot guy, but THJ has better ball-handling skills, so he can "create" his own shot. It's a swap between catch-and-shoot guys.
Why the Pacers do this: NY seems like they gave up on Randle, so, finding a new home is primordial for him. Indiana seems like a great place for him, he won't be the main guy (Brogdon is), so there will be less presure on him, giving him a chance for redemption. Also, they get a young wing in Green, still needs to upgrade his 3-ball but overall is a below average passer but a great developmental guy. Bertans brings 3-point shooting, a great shooter off screen who can knock down great shots. PD: Kemba brings depth at the PG.
Why the Knicks do this: Turner is one of the best C in the league, replacing Randle with Turner is a massive upgarde: better defender and better shooter. Pairing him with guys like Barrett and Rose would be an interesting combination. They also add an efficient 3-point shooter in Hield, who also has average at best ball-handling skills.
Why the Maverick do this: First of all, re-signing JB is the top priority, giving him 15mil/year is a bargain and a friendly contract. Second, finding a C who can grab offesnive rebounds and protect the rim is a top priority also but, can we get all that for cheap? Maybe yes. Mitch Rob is an amazing rebounder with great defense, IMO, he is an offensive-skilled Gobert: great paint presence, amazing pick & roll guy, great rebounder and has a bigger wingspan than DP. Micth Rob looks like the best option for Dallas if they wanna go cheap.
Disclaimers:
Nobody wants Powell, so, a dead contract seems like the best option.
Duncan Robinson fits so well with the Mavs scheme: a 3-point shooter that shouldn't be too worried about creating his own shot (you have Luka though).
Knicks roll with Rose, Burks and Quickley at the PG, giving Quickley an upside as the PG of the future.