Really can't sit change up the way the guy is pitching and the way the ump is calling this game. If the pitcher can get both his FB and change for strikes in good locations or with this ump off the plate even, your goose is cooked.
You really want to sit FB and if he misses with location on the change, just stick your bat out and dump the ball into the outfield. If you sit change you will never catch up to the FB.