He's an assassin that plays like a bruiser. when he gets caught out by your team, it's still your own team who will suffer since you're punished for not letting him escape by getting your whole team stunned (this is the reality of soloqueue since everyone will attempt to get that finishing blow).
Even when you get him low for him to escape he heals it all back up in a matter of seconds and comes back to ult, and he can ult over, and over and over again. While other assassins suffer from the fact that if they mess up their assassination, they have to wait a substantial amount of time before they can do it again, pyke completely avoids, and can repeat just after a few seconds. and if he does mess up, well, he can stil be useful with a few stuns, maybe get a hook as well.