[greymule]

That's a tough one. As others have pointed out, umpires are of two schools on this. I've always believed that the fielder's obligation was to hang onto the ball, but that the requirements were not as strict as for a catch of a fly ball. If an outfielder catches a ball on the run and then after two steps crashes into a fielder and drops the ball, it's no catch. But if F3 caught a throw and the runner crashed into him after two more steps, I'd call it an out. One step? Half a step? HTBT.

And what of the other variations? Fielder has the ball, stumbles toward the base and then trips over it before the runner gets there. Then he falls, rolls over, and drops the ball. Safe or out? What if the runner collides with him during his fall?

What if the throw draws the fielder's arm into the runner, and a split second after the catch the collision jars the ball loose? I'd call that safe (as long as the runner was running as he was supposed to).

On the other hand, I do a lot of softball, and in that game that play is an out. ASA has specifically ruled that after a force play, a ball dropped as a result of a collision is still an out.