No clear look on fast break...

[doubleringer]

I agree with everyone else. If you don't see it, don't call it. How would you defend a guess to a coach? If you get asked about the play, don't lie. "Coach, I had a player run in front of me right as the shot went up so I didin't get a good look. I'll work hard to make sure it doesn't happen again." If the coach doesn't get that, then an opportunity to blow your whistle may present itself.