I agree that handling a double team is hard, and that's why I question how Nate is supposed to handle this as an adjustment between games 2 and 3. We can speculate that Nate isn't doing his part to help him handle a double team, but it would be pure speculation unless you're privy of seeing practice. Obviously the entire coaching staff needs to address rotations out of double teams, and the players need to be able to retain this information. I've noticed guys like Andre Miller and even Greg Oden are much more patient in double teams and don't make the simple first kick out pass (that the opponents want you to make), but they make the defense commit elsewhere and get the ball to a player in position to score. So if a young guy like Oden is able to make proper reads out of a double team, then maybe he's got a much high IQ or make he's able to retain what the coaches throw at him.
As you may or may not know, I get to log a lot of games in the NBA, and a ton teams switch pick and rolls as much or more than Portland.
Golden State, Denver, New York, Toronto, Orlando, Boston, Lakers, and the Thunder (of the top of my head) switch a ton. Fighting through a screen is always the #1 option, but it's an unrealistic expectation.