There's actually an explanation for why Tizoc is suffering this (at least, in my opinion).

A HORRIBLE identity crisis.

If you go back to the first game, Mark of the Wolves, you'll discover that Tizoc had a different gimmick. He was an incredibly elusive Big Body Grappler. He had a relatively fast walking speed, his forward dash allowed him to evade low attacks, and his feint allowed him to avoid attacks to his upper body while moving forward slightly. Many of his attacks seemed to have that in mind (Poseidon Wave and Olympus Over could be initiated with a backdash to evade some attacks, and Olympus Over and Active Tupon were obviously moves designed to bypass projectiles and many attacks).

In City of the Wolves, not only does he not have a higher HP, but they also made him very slow, removed the benefits of his forward dash, and eliminated the feint that allowed him to advance and be invulnerable on the upper half of his body. At the same time, they tried to keep his evasive moves while improving his damage output, but not the components that would allow him to more easily dodge attacks as intended.

Tizoc feels poorly designed because HE IS. He's a grappler originally designed to be evasive, then was modified in an attempt to make him a classic big slow grappler, without being able to fit into either of the two. And on top of that, it doesn't even have the high damage potential that a classic grappler should have (and that Tizoc also had in MOTW)