Blaze Attacking from long distance

This is on a Realms Vanilla (obviously) Survival SMP Server.

While digging out a large area in the nether, Blazes are attacking from 50-75 blocks away. I know they can "call" others up to 50 blocks away, but I thought that was just to move closer, then shoot when they're in range. Regardless, I looked around and there weren't any closer than the ones shooting. (Screenshot attached of aggro'd blaze, the others were in cooldown, and I've been attacked from further away too).