I think he is mostly fine you are just super dependent on your DPS picking up on your cc to confirm kills, I would imagine in pro play he is going to be one of the top tanks.
Think most of his problems can be solved by some number tweaks with either slightly more damage on rocket punch, lower cooldown on slam and more ult charge since its such a low impact ult and takes forever to get because he does such low damage.
Personally think slam having a lower cooldown would be the best bet.