I think you're giving up such a good FG% because your players are too tired. That'll kill you in the press. You've generally got good stamina ratings -- if you put your starters at fairly fresh and your backups at getting tired, I think you'll see better D.
Occasionally for big games I'll set my best player or two at getting tired, but only when my bench players are much weaker, because the press tires players out so quickly that any longish stretch without a stoppage in play will completely wear your guys out, and they seem to have trouble recovering from that. It's the only real downside to the press -- it's hard to maximize your best players' minutes.
Also, running slowdown when you've got stamina issues can really hurt you, because you're much more likely to have those long stretches without fouls or turnovers.
You have good staminas in general, but you are carrying a walk-on, which I try not to do in the press, and only having two PF/C's is kind of like having stamina issues. (Hey, I don't mean it THAT way.)
I'd be tempted to have one Big backup for the other, so you'll always have at least one person who can rebound in there. Then again, if they're both listed as starters, at least they'll both be in there for crunch time in close games.
As to your question about defensive ratings, I'd say not to worry about them. In D3 you're just not going to have everything. I'm with cthomas22255 on this. SP+ATH, although I think STA is vital. If a guy isn't going to get to 80 stamina, then I don't want anything to do with him on a pressing team. And he'd better get there sooner rather than later.
Oh, and I think if Mosely was set to Fairly Fresh then he'd do a little better with his free throws -- man he's been atrocious.