Endurance is a part of this compe ion, maybe he thought Murray could beat him at that too, you never know.
I think we all knew that Tony could beat Patty for the spot, I think a good thing to view all this is to think that Tony believed that Murray and White would be very good players and that it would be hard for him to outplay both of them. Which is a great compliment from Tony to our younger guys.
I also believe that he knew in advance that Manu was leaning towards retirement and that influenced him about deciding to leave, same way as Manu decided knowing Tony wouldn't be here. After all they were also good friends.