Your point is valid. The Miami Heat were underrated in the playoffs; not only did they defeat the Bucks, but they also overcame the Celtics – both formidable teams. In fact, these two teams were considered stronger contenders for the NBA championship compared to the Nuggets. The Nuggets gained strength as the season progressed, especially with Jamal Murray returning to his old form.
As for the Bucks, it's possible they've been somewhat complacent due to their previous championship win. Their early exit from the playoffs could be frustrating for them. They've taken a significant step by replacing their coach, and with a new coach in place, there's potential for change. The Bucks might regain their momentum and return to the Finals. However, consistency and maintaining good health throughout the season will be crucial for their success.
Yes, we don't like coaches being fired, but they are the first casualty if a good team suddenly become bad specially in the playoffs. They have a good lead against the Heat, however, they can't close them and on the contrary, they were beaten. So I wouldn't be surprised if the Bucks started bad in the first half of this season and then coach head getting rolled as a result. So let's see, hopefully this is not the case for the Bucks as they didn't have any major changes in their lineup, meaning they will go for another good run this season.