Catcher Batter Contact

[tankmjg24]

Middle School game with FED rules. R3 with two outs and a 2-2 count on the batter and F1 throws a nasty hook that drops right off the table and bounces off of home plate into F2. Batter swings and misses and the ball is blocked directly up the first base line in the runners lane about 30ft from home. F2 immediately jumps up and takes off up the line in foul territory to get to the baseball. The BR takes off down the line to first base. F1 also begins to run towards the baseball. About 20ft up the line F2 and the BR make contact with each other and both fall to the ground. F1 picks up the baseball and reaches over and tags the BR who is laying on the ground.

I am the third base umpire so I was just playing spectator for the play. PU initially signals obstruction but then upon the BR being tagged by F1 he points to the first base umpire who signals out. At this point the plate umpire signals me and the other umpire in. He says that he originally had obstruction where contact occurred up the line but then thought it was incidental contact where it was F2 and the BR who collided. They both were doing as they were supposed to be doing and just so happened ran into each other. The first base umpire immediately agreed with him.

My understanding of the incidental contact ruling is that the contact has to occur within the vicinity of home plate. With the contact occurring up the line is it still incidental contact? If a call should have been made, would it have been OBS or INT? It really was a weird looking play with the two colliding the way they did.

Also for my own knowledge, what if it had been F1 and the BR who had collided? The way they were both running it seemed as if the contact between F2 and BR had not occurred F1 and BR would have hit.

This is probably a HTBT but opinions are appreciated.