I wouldn't call it unfair, as it is not a guaranteed 'ship in any league of any cap.  It's strong, and it's super unrealistic, but it's not unbeatable by a long shot.  Not going to tell you everything, but here's a start:

Don't try to hold an ultrapass team to 50% or less from the field; you won't do that consistently.  Try to hold them as low as you can while getting enough possessions to make more field goals than them.  Rebounds actually are a key part of it.  You're only thinking about when they're shooting, when you need to be thinking about when you're shooting.  These teams typically have decent drb% while having terrible orb%.  Here's an example:

If they shoot 48/80 with 20 ftm & 8 3pm, they score 124 points.
If you shoot 49/98 with 20 ftm & 8 3pm, you score 126 points.

So they're shooting 60% & you're shooting 50%, yet you win.  How? You got off enough extra shots.  You do that by getting second chances on your end, grabbing up the few shots they miss on theirs, and limiting your turnovers.  Those high ast% squads typically turn the ball over a ton.  They also tend to not go to the line as much, so that's another area in which you can take advantage.

I've had a lot of success both with and against the ast% squad, and the squad that does the best usually revolves around 96-97 Jordan, a Chris Paul (used to use 11-12, but now would probably use 14-15) & a rotation of Shaq at center (lowest defensive rating of the ast% squad teams usually is at center).  That's high defense, low turnover, solid efg% & then killer rebounding (lots of worms).  I just lost in the conference finals with a high-ast% strategy.  The team that beat me?  14-15 Curry, 12-13 Lebron, 92-93 & 94-95 Worms, 76-77 Walton - quite the starting lineup!  Lot of boards there.  Lot of defense.  Good efg% itself.  Very hard to handle.  I just made a run with another squad that beat a high ast% on the way.  That team?  94-95 Stockton, 12-13 Lebron, 92-93 Worm, 14-15 Noah, rotation of Shaq.  Lot of boards, good defense, high efg% & enough assists to make that efg% even better.

So, with the right lineup with the proper coaching adjustments (which I have not and will not go into here), you can take out an ultrapass squad in a 7-game series.  It's like anything else in the sim: a series of tradeoffs to get the highest statistical chance of winning the right die rolls at the right time. 

Good luck.

Thanks ash! That makes sense. Maybe unfair is the wrong word its just like you said hyper unrealistic. That's great advice

I almost never use the strategy (I think I did like twice and it was boring) and I can generally always get a top four team and handle the assist teams....  and I dunno, I am not a savant or anything by any means.  A huge number of owners are way better at this than me, but I enter like one open league team a month and always do well (except for that time last month when I accidentally entered my progressive team into an open league!),

Anyway long into, but I usually use something like either an affordable Wilt season or a beefy combo of some random partial seasons, Rodman(s) at PF, shooting/boards/defense at SF and solid usage and shooting at the guard spots.  Generally really low TOs and Fs across the board.

I guess it is formulaic but those teams perform really well against assist teams and I think it validates much of what ash was saying.  High boards, high defense, shoot well enough, don't foul or turn the ball over.  It works.

Just realized I was the three weeks late on that response.

Imo..high blocks..high o- rbds & +1 def tends to disrupt ast. Using this my team typically rank league high in holding ast down. Try getting bump @ 25apg...

Should I use a half-court offense countering the Assist squad? And my team has good defense... PRESS? Thanks

Press helps increase their already high fg%.

Half-court or Slowdown are helpful against a superior opponent, particularly one that relies on efg% overload.