Bucks definitely has a deep squad, and with Lillard they actually got that second super star they need to win a title too, so they should in theory be good enough to actually go for a title. For a while at the start of last season it was hard to get used to each other, but this season they should have been even better. In any case, I am sure they will do fine, not sure how deep their playoff run will be, but they need to fight for the finals, there is a possibility in that team.
It's more of the adjustment on their end, and I think they start the year as not healthy as like now, so it's a bad start for them and then we all put the blame on Doc Rivers. For sure Rivers have read all the critics and then he comes back and silence him with a good performance by winning the NBA Cup and Giannis and Lillard doing it all along. Specially Lillard who seems to have settled down in the Bucks already as like his old self with hitting those 3 points like a prime Dame Time.
Between Ante, Lillard, Middleton, Lopez, Portis etc etc, they really have a good squad that is worthy of a championship. At that point, if they fail with such squad, I would just fire the head coach and get someone else because they really should be there. Look at Celtics, they did so great, and only had Brown and Tatum, the rest aren't that great, Holiday and White and maybe an old Horford? Not really a big deal, so Bucks definitely has what is required to win at the moment for sure.
Middleton, Lopez and Bobby Portis are part of their core that won their ring the last time. So they have the experience to pull through again if they remain healthy and then their second enough also playing hard and giving them good quality minutes while the starting five in resting. They are in the 5th position in the East, so that is good enough for another playoff run or they can improved it as high as 3rd place in the standing.