Yes you do, the server would 100% of the time leave the mage as gouged if you gouged him at the same time as blink. You could 100% vanish a death coil, every single time without fail if you timed it right. You could sit out there in durotar and do it over, and over, and over. The behavior was not undefined/random, it was consistent and predictable. In what way is it not?