I consider myself a veteran but by no means an expert since I run just one team.

Any thoughts on why this team sucks because I don't know WTF IS WRONG?

https://www.whatifsports.com/hd/TeamProfile/Ratings.aspx?tid=7628

It only looks like you have one bad loss? (St. Thomas, maybe Central)
Most of the other teams you've lost to look like better teams.

Also, I think it's strange that you run Flex but only one guy shoots 3's.

From my understanding, flex is not good for the kind of offense you are running. Having one guy score 20 a game and everyone else under 10 a game. I would try to even out your scoring a little bit. Also, your bh/pass is a little low, I'm not huge on the 54 team ATH either. Seems like a good team though, you don't really have that many bad losses.

Sucks is a huge overstatement and is the main reason why I am commenting. At a quick glance, you have one BAD loss this season and playing a tough schedule.The rest of your losses are against high quality teams. Playing a schedule like this will give you a reality check on the quality of your team before tourney time and it looks like you might be on the border of Last Four In/Out with your current RPI. Looks like this definitely isnt the most talented roster that you have assembled so count this as "rebuilding" season and build up for next season.

Are the better coaches attacking the 40 DEF C? If they are move him around so he covers the smaller threat in the post. He should be able to play the 4 or 5.

Also, like others said, I would recruit more PER/SPD for flex teams and consider this a low end NT quality team. Just try to make it better each season.