Robbing homeruns is actually pretty simple in MLB The Show 16. There will be an indicator to let you know if there an opportunity to rob a homerun. This does not always necessarily mean you will have a chance every time, but it means it will be close.
You can either hit the RS up or just us R1 to start the animation to rob a homerun. I prefer using the button since it is a bit easier to control. Sometimes with the RS, you will accidentally tilt it up and to the right/left and your player will not jump. Once you see the last orange ring, right before the 3 final inner red rings, you want to just simply hold R1 to start the animation.
There is a little more to it then just to going back and hitting R1 though. You want to make sure you follow these pointers:
1) Determine how much you have
This means you need to determine the trajectory on the ball. If it is a liner and you see the rings disappearing quickly then you need to take a straight path. If it is a higher fly ball that is going out then you need to walk back and make sure you can gather enough momentum to run at the last second and hit R1. You usually cannot just run to the wall and hold R1 without momentum.
2) Run in a straight line before prepping jump
If possible always try to go straight back on the ball and try to avoid going at the wall at an angle. Sometimes you do not have a choice, but if you do then try to get directly in front of the indicator (about 10-15 feet) before you run straight back at the wall and making your jump.
3) Hold R1 when you see last orange ring
Again…you can simply just hold R1. The timing mechanism is very generous here, so you want to hold R1 at this time to get the best animations. There is no reason to risk it and press R1 too late.
Follow those basic rules and it should give you the best chances to rob homeruns more