Had a similar experience in terms of catapults, there I was with a meagre force of 650 Byzantines against 1700 Spanish Crusaders, I thought to myself "Find a hill, hold it aslong as I can, do as much damage as possible" simple, lose but make them pay for it.

I had 1 catapult team, that had killed squat in the 2 previous battles they had been in so I vengefully put them at the back of my army, the battle starts and the map turns yellow as a load of Spanish come towards me.

First thing I do is click on my catapult and order it to fire, randomly clicking into the mass of Spanish, first boulder goes absolutely miles away from where I clicked bounces over the Feudal sergeants crashing into a unit of Royal knights killing 1 man, who happened to be the enemy general.

Laughing hysterically at the joy of such absurd luck I ordered my trashed units of treb archers to fire down at the Spanish, within a few minutes the crappy units of the Spanish army are running for their lives and the better units can't withstand the charge from my 2 full Varangian units who whilst outrageously outnumbered piled into the Spanish routing the lot of them. I then unleashed my fierce -1 morale horse archers units to chase them down. After about 20 minutes of chasing, routing chasing the stats were 400 Spanish killed and 900 captured to a wonderful 87 Byzantines. The most ridiculous thing i've ever seen.