Why don't we see more of Gyrocopter?

His stun was redone a little bit for a guaranteed (kindof) 2.5 second stun. His first skill is decent early game. Flak cannon gives really good lane harass and farming and late game carry potential. His ult is good teamfight AOE.

I know he doesn't have an escape mechanism, but plenty of heroes that see play don't have them.