Considering how popular haze is it shouldn't be possible to play only as one all the time, yet I've been carefully testing and analysing this bug for several dozens of matches straight. Basically, it allows you to bypass current rules and secure hero you want.
Assign high priority to the hero you want to get, medium priority to the hero you never played (have 0 games), low priority to any hero.
Example: Haze high prio, sinclair with 0 games medium prio, vindicta and calico low prio. Now you get haze 100% of the time.
I guess it could be replicated in different ways, the key factor seems to be having hero you haven't played be assigned with lower priority than the desired hero.

Assign high priority to the hero you want to get, medium priority to the hero you never played (have 0 games), low priority to any hero.
Example: Haze high prio, sinclair with 0 games medium prio, vindicta and calico low prio. Now you get haze 100% of the time.
I guess it could be replicated in different ways, the key factor seems to be having hero you haven't played be assigned with lower priority than the desired hero.
