ok, i found it ... here's that opposite rule-of-thumb post (re: jhawley)
so, when teaching umpires, it might be unwise to bias them one way or the other on this issue ... better to get them to to reason out their own judgements
this is copied from another umpire site, at
http://www.amateurumpire.com/others/jb/jb01.htm , written by a fellow called Joel Balberman
#7 TIE GOES TO THE RUNNER
It is commonly believed that there is a rule, unwritten or otherwise that tells umpires how to call the close ones. That belief is that a tie on a force out should result in a safe call. As umpires we make decisions on every play. We cannot say: That was too close. It's a tie! The choices are twofold: out or safe. The runner either beat the play being made on him/her or he/she didn't.
It a well known joke that there is only one way to call the close one - out! Why? It helps to get the game over with faster. Obviously, this is not the way we should be operating as umpires.
A better rule-of-thumb might be: If in doubt, never out.
This may be a new way of thinking about close plays for some of us. It is worthy of some thought. There is another way of looking at these plays as well: Did the throw beat the runner to the bag? Did the runner clearly beat the throw? If not, the call is easy.
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regards ... bob