Mind Control is offered about 3.5x more often than MCT (.7 times per draft instead vs .2)
Mind control is better than MCT, so is picked more often than when it is offered. According to the lightforge (and its probably not much different on heartharena), Mind control is rated the 4th best priest common card... so you pick it almost every time it is offered. MCT is the 25th best rare card, it is slightly above average, so you pick it about 1/2 the time it is offered.
Sometimes (20% of the time?) it is reasonable to play MCT without triggering the battlecry (like on turn 3 if its ur only 3 drop), whereas you have to wait until turn 10 to play mind control and you generally don't waste it on something small.
When played Mind control takes the minion Ozruk 100% of theim. MCT takes it 25% of the time.
Multiplying these together 3.5 * 2 * 1.25 * 4. Mind Control is about 35 times more likely to take Ozruk than MCT (not even accounting for the fact that he is at 6-0, so it is more likely his opponent has good, consistent cards... e.g. Mind control rather than MCT.
It is relatively unlikely his opponent takes the Ozruk with MCT.