the bucks were one of the best teams last year and lost to the eventual champs in 6 games and the total point differential was like less than 10 points overall for the series. they lost one good player from last years roster but brought most of the guys back and still have the reigning MVP who can get even better. they should be one of the championship contenders next year. should note that next year is a lot more wide open than it has been in the past, when it has been one or two team competition. now it's up to half a dozen or so. they project to be good long-term if they can keep giannis, who is UFA in 2021. not convinced he's a buck for life but we'll see.
mavericks should be good long-term as they have one of the best young players on their roster in luka doncic. they added kristaps porzingis last year who has durability issues but when healthy is a very good young player who has great upside and whose skillset should fit well with each other. mavs play in the west that has been the tougher conference for a long time. they could battle for one of the last playoff spots but likely won't be more than 1st round team next year.
neither team probably won't be bringing lot of good youth in the coming years. bucks are a good team so they will be trading away picks and when they keep them, they will be late where it's hard to find good players. mavs traded their 1st this past draft for luka and they also traded couple of 1sts for porzingis. they have their 1st rd pick next year and that pick will be their best chance to bring in a good young player to their roster short-term. they should get good in year or two so the picks they have will be late. jalen brunson, point guard, drafted last year and showed some promise for them.
bucks have khris middleton who qualifies a s a star and whose skillset fits well with giannis. giannis will have the ball in his hands a lot but in order for the other team to stop him, it opens up other opportunites for other players. bucks play well as a team but are build around giannis. they have quite a few players who get plenty of shot attempts besides middleton and giannis.
mavs are bit of a questionmark since they added porzingis and probably make some adjustments based on his strenghts. neither luka nor porzingis is a great athlete so they should be moving the ball a lot. playmaking is one of lukas strenghts and porzingis is a great shooter so they won't be limited to feeding those two guys but those two are their best platers by far so they will focus on feeding those two players.
mavericks beyond luka and kristaps aren't very good. they'll go as far as those two carry them. they have couple of solid players but they'll rely on those two guys. mavs kind of missed in FA like they do every year (don't expect star UFAs as a mavs fan) and their HOFer dirk nowitzki retired after last season so they are just passing the torch to these guys and it will take some time to shape up the roster.
giannis will have the ball in his hands a lot. which makes sense since he's their best option at scoring points and reigning MVP. stars impact the game in basketball a lot more than in hockey and in basketball teams will feed their stars a lot. giannis was 5th in usage rate last year (luka was 11th) which is an estimation on how much particular player is involved on plays the team makes while the player is on court. he's not a selfish player, not a great shooter and he's playstyle is physically demanding so he'll involve other players as well but their success will largely depend on how well giannis plays.