I believe about 40-50 ish Yoggs since the "nerf" that I have played or have seen played have had barely any bad card choices. At most 1-3 buffs for the wrong team, and a bunch of good spells. Only a few times have I seen Yogg kill himself either.
I would say RNG despite the huge amount of good plays, but it would also make sense if they reduced the chance of "destroy" cards now that Yogg can kill itself.
Hows your experiences from the almighty Yogg?