Having a system to strictly follow in order to hand out punishments is not a good idea really.
As Dynamics said, he (or anyone involved really) put days, or weeks, maybe even months (if he is slow) into gearing up armies and stuff.
Then some moronic people decide it would be funny to have the entire enemy team banned, thus making all those previous efforts null and void.
Now I do not consider this a major offense, but those people involved probably had a good chuckle and had a wank for the rest of the night, just to hop back on cRPG the day after.
While at the same time, those people losing their army are incredibly frustrated and demotivated to even continue. Because why does anyone need to work in order to get an army, if they can just attack with 100 unarmed people and then get the enemy team banned, for a mere 24 hour ban?
For such a case your system needs a "Adjust punishment accordingly to severity of offense"-clause.