I usually hold CPU to below 50% on threes. I try to stay home on my man and use a lot of L2, either alone or with right stick forward rather than jumping. Jumping is really only for closing out when I'm late or when I know they're putting up a shot late in the shot clock. I also don't immediately switch off my guy if they pass it but pick up the ball handler when it's not so chaotic and deny the pass back to the original passer. I play the Warriors for what it's worth, and we've been terrible defending against the threes lately in real life. :P
My 3 point percentage is pretty close to the real Warriors as well, around 40%.
I do usually win most of my games with these sliders. Not sure how I'd fare with another team but the Warriors have weapons and staying home and playing defense with position and proximity rather than jumping has worked for me.