Organ gun OP?

I just played an arena match 4v4. I was playing as chinese on flank and my pocket was mongol. Our opponents were Byzantine and Portuguese players. In early imperial age, we had a decent composition, of mass Elite Chu ko Nu (with rocketry teched in). The mongol player had a mix of cav archer and Mangudai. We were pushed back and destroyed by the combo of cheap skirms and few mangonels from the Byzantine and the Organ gun and halbsfrom the Portugese guy. Basically, we could not push back. Every time we tried to engage, the mangonel and organ gun would shred our army and skirms would tank all the cav archer mangudai + chu ko nu arrows. Yes, we could have teched into Onagers ourselves but those Organ guns did not give us any chance to get close to them. The Organ gun as a backup firing unit is quite OP. What do you guys think?