I like Middleton alot. I often trade for him because his combo of shooting and defence.
Drummond is a stud at his position because of his physical ability.
Dunn is good but he's years away from reaching his potential. I did play with him once though and he played above his overall rating IMO. Not sure about Johnson.
Actually the team has 3 good starting players so that's not too bad. I don't know about your bench but that might not matter if you play short quarters. I play full game (12 min quarters )
I guess a tip I have is that there are a few good players you can get as free agents. I don't know if you'll enjoy them.
Stephenson has a decent game all around. Nate Robinson is good for his speed and dribbling. Thomas Robinson is decent and has great rebounding. Shit and there's a point guard that's youngish around 24 and has a rating like 72 that overperforms for me. I forgot his name. I usually get these players every game because they're good bench players. Fyi you may need to release one of your crap players to sign someone because of roster number limits.
As far as economics it can get quite complicated but it tries to copy real life so you can read up on the NBA for that.
I do notice in the offseason you can get alot of free agents if you fill their green bar to the top(a bar you'll see when you offer them contracts).
Here's the cheapest strategy I know to get a good team in a year:
Trade all your good players for young players with potential or preferably draft picks. Keep your pick. Ensure all your non-young guys are on expiring deals (1 year of contract left). Finish the season, you'll probably be one of the last teams in the standings and will get to draft a good player in the offseason. In the offseason sign as many good free agent players as you can with all the cap space you have. Then you can trade your picks and young players to fill out your roster.
But I don't know how much satisfaction you get from a game like that. I prefer playing with average teams.