one in four years

[Lotto]

My view is that block makes it certain that the ball isn't going in the bucket, so the try has ended before the ball leaves the shooter's hand. Hence no loss of team control, hence no backcourt violation.

Another way to look at it is that the ball hasn't been "released" as part of the try, but rather swatted away by the defender.

The comparison to a batted ball while dribbling seems quite a propos here...