Otherwise, he's fine. He's so easy to kill considering how long his attacks take to finish. I can't count how many times I've killed a Zeus charging his ground pound with Sir Dan's level 2.
Jak can get 6 kills with his level 3, your argument is invalid.
There are many characters that can yield 5-6 kills with their level 3. This depends on map size, opponent locations (scattered vs in one area), how well you follow your opponents/how well your opponents move, and how powerful the level 3 is.
With Zeus, you are confined in a small, flat area where he can reach EVERYWHERE! Granted not everywhere at once but is difficult to dodge him. Simply put, he has the best level 3. If we consistently tried each level 3 for each character, I'm sure we would find the highest average with Zeus. I'm sure Jak would be up there as well. But Jak doesn't that sort of AP gain. Players who are getting level 3s with Jak put in work.
Zeus is slow and sluggish. If you manage a hit, you get AP. He is pretty balanced IMO. However, his level 1 sucks. His level 2 kind of sucks too. A lot of players just go for his OP Level 3. Once he reaches this, he goes from last place to first place.