My approach in the game against you would have been to attack your front with outside shooting. I would have played reverse patient. Your opponent took the same aproach. In this case it seems to be very effective.
Also looking at his games, losses mostly, if he loose, the loose by few points, all the games in the season for him was quite competetive. It is indication of well balanced and managed team.
20OD is surprising, 8ID toolow for defending against inside and some isolations, but in this case it desnt really matter.
Salary doesnt mean anything, i have 8k 14OD guy and used to have 15RB 15 ID guy of 16k salary
Bad shot distribution is usually of the lack of passing in PG spot or very high lack of passing in the other spots. It depends on the style mostly, but i generally dont want anyone in the team to have anything below lvl 7 passing. Also lack of passing in some positions leads to bad shots from wrong position.
Also your offensive flow might have been diminished if his SF-PF-C guys had good OD.
My aproach is that the lower the offensive capability, the higher the passing of player should be. Players in offense either shoot or pass the ball. So the starter should have either shooting of passing.
Anyways sometimes Game engine is hard to understand, sometimes i loose very unexpectedly too. But i have to admit that the suprising wins are as common as surprising losses