[mbyron]

Here's how I think of this question. Suppose you let play continue. How long will that take? 10 seconds? Can't the average batter runner get around the bases (4x90 feet = 360 feet = 120 yards) in less than 15 seconds? That's not much time.

So now ask yourself: in what kinds of cases will 10 or 15 seconds make a difference? That's the only difference between stopping play immediately and letting play continue.

One answer has already been given: if the injured player is at risk of further injury, then kill it.

If the injured player is unconscious, has stopped breathing, or is bleeding from the ears (serious head injury), then 10-20 seconds can make a difference. If the injured player is cut so badly that you see arterial spray, then you also need to stop play. These injuries are quite rare, but if you happen to see you address it immediately.

Some guys add a compound fracture (bone sticking through skin), which is kind of a gross injury and has additional risk of shock. It's not, however, life threatening, and 10 seconds will not make a difference -- it doesn't meet my test.

Otherwise, let play continue. If a coach complains, tell him that you saw the injury, that by rule we play on, and that the 10 seconds needed to do so didn't make a difference to the injured player's condition. Heck, the first 10 seconds they stand around an injured player and ask where it hurts.