Ball strikes runner

[joemoore]

I think the rule is being mis-read.

The phrase "...In making such a decision, the umpire must be convinced the ball passed through or by the infielder and that no other infielder had the chance to make a play on the ball..."

The ball must be untouched (through or by) and the other fielder must have a play in order for it to be interference.

Why else would the umpire have to be sure that the ball went through or by the fielder untouched? The only way the rule makes sense is that there is no interference on a deflected ball.