Parker averaged 20 points per game last year. However, the Bucks actually played better without him. The problem the Bucks found themselves in is it was hard to play Parker and Antetokounmpo together. Although Parker shot the ball better last year he isn’t a particularly good shooter and he also needs the ball in his hands. So, the touches he was getting was taking touches away from Antetokounmpo, who is far more effective with the ball.
Parker also doesn’t do very much defensively. Antetokounmpo already does so much defensively for the Bucks it’s hard to ask him to do even more when Parker is on the floor.