The same kit without leech wouldn't seem as broken. But thats because of overloaded kit. Propably taking away any single of his features would make him much more manageable. In most 1v1 scenarios currently he's always full hp as long as opponents backline is alive (and thats all leech fyi). And after that, when it comes to 1ninja vs 1 ninja he doesnt heal that much, but because of dodge, immunity, mystery every round with self chase (or every 2 rounds vs not immune dodge ninja) there arent many ninjas that can compete in such scenario. Thats why everybody is running sosp, because when it comes to that 1v1 you are fighting on even terms. You both can do the same.