colliding opponents

[walter]

As long as neither player put the other at a disadvantage before the collision, you have nothing even though the contact could have been severe. It sounds like you had two players who simply got to the same spot at the same time and ran into one another. It happens and it's a no call. My only advice is that you work to get good coverage angles so that you see the whole thing happen and truly can see if there was or was not any advantage gained by either player.