I'd say you have it backwards. The My Career teammate AI is not significantly different than the AI for normal play. You are relying on teammate player tendencies to fill in the blanks that would normally be filled by a user.
This is why you can pass to wide open shooters in the corner and they dribble into traffic instead of shoot. Their tendencies say they should drive more than shoot, so you get a crappy shot instead of a good 3 pointer.
This is why boxouts are hit and miss. The CPU assumes that if you really wanted to get the board, you would switch to the bigs and manually control the rebounding.
But you get good stuff with this too. Instead of scripted cuts away from the ball, you can control dives and call for the ball when you get an open lane. Your player can pre-emptively move into position for a rebound when the shot clock gets low. You can rotate intelligently on defense to make up for your AI teammates.
It's just learning the new places where you can break down the opposing team, and learning to use your teammates' tendencies to your greatest advantage.