Numbers don't lie, that is exactly what happened. You can compare the numbers for yourself, but here they are just incase you don't want to:
Al MPG 2011-2013 36, 34, 33
Al usage rate 24.2, 25.7, 25.3
Paul mpg same time: 34, 32, 30
Paul usage rate: 22.6, 23.2, 22.4
Gordon MPG same time: 17, 30, 29 *edited because I originally put 80 for the second season...
Gordon usage rate: 15.3, 17.8, 22.1
Gordon was always second or third to these guys. It is very clear. I didn't look up Mo, but to me when he was on the court together with Hayward, it was not a good fit, and Mo was a ball hog.