Unfortunately, not only did they nerf his True-damage power with a health meta, which True damage hates. But they also nerfed the cooldowns on his W and E, removed the bonus armor pen on a non-active R, and made Q's horrible slow degrade with time.
overall, Olaf's still a strong duelist, but he can only duel when all his moves are off cooldown, and he can't stand prolonged fights anymore. You're not going to be pulling off your famous Olaf Jungle invades and getting kills on Brusiers. You can't chase worth a damn, and your fighting ability is cool-down limited like Xin Zhao, only you can't chase STILL.
Ignore the silly passive armor pen the ultimate. Lower Olaf's W and E cooldowns back to normal, and perhaps..just perhaps fix the Q slow-reduction, and he'll be able to fight again.