Ok....
Say the impact area is 50 sq/inches...
Then your Pounds per square inch (PSI) is: 415.55 lbs per 50 sq inches...
Or 8.311 lbs per sq. inch
Coach you have to remember, force of impact (like car crashes) are not measured in PSI... they are measured in Force (Newtons or Pounds-Force as stated earlier), which is why we calculated how long the collision took place.
Its hard to calculate this on paper, but The size of the player will positively increase force, the bigger he is, the higher the force, but it will most likely also take longer to stop him (time of collision), and the longer the time of collision is, the less force there will be experienced by said player.