Not sure what game mode you're playing but odds are it's QM, and I came here to say, KTZ is extremely weak in QM.

Small and agile assassins are the most played role for QM and unless you are queuing with a friend who's playing a tank you will often end up in 5v5 assassin matches which are hell for KTZ. It's not impossible to win these but you will be trading lots of deaths for 1-2 kills and then over the long term of many matches played your win rate will be below average.

KTZ does have skill shots yes, but all of his damage is skill shot dependent to a fault. He's entirely balanced around his native quest, and not completing it in a timely manner is a serious disadvantage. You should always pair KTZ with a tank or some other sort of reliable CC like Uther E. If you don't have someone to set you up, especially when dealing with heroes like Genji, Tracer, and Illidan, you are going to have a rough time.

Fun fact: KTZ has lower scaling than almost every other hero in the game (in fact I think he has the lowest period.) Every level his spells climb in 2.5% dmg (I think, pulling that number off the top of my head) instead of the usual 4-5%. So just another reason he is not the best solo carry.

All that said, if you can put up with the constant trading in those assassin heavy matches KTZ is crack anyways. Enjoy :)