Have you thought about relaxing the distance/proximity requirements for detonating the grenade? It looked like there were a few cases where the grenade passed close enough to do major damage without being detonated. It could be effective to deploy all the lances in a fan pattern when space allows to give it more chances to get one of them into range.
I increased detonation distance for fight with bigger bots.
The problem is that Lancer usually damages itself, and with increased distance to do it more often (detonation of almost deployed grenades), so I try to keep distance as low as possible to avoid damage to front wheels (it happened a few times). Also if target part is too close to grenade, Lancer looses target for a short time because there is some space around grenade that is not covered by cameras, these situations can be mistaken for too low detonation distance.
Deploying multiple lances should work great given enough space and some elevation control.
Perhaps now would be a good time to add some new variations on the basic ACL to keep things interesting.
Sumo - there are infinite forces, infinite masses and partially broken physics. It will need rules to control this.
Air - would be nice. I am not sure if fights in a spherical arena would be easy to watch. My zero gravity big bot construction map (a closed box) is quite unpleasant place, camera is bumping into walls and has weird direction controls.
Death race - it would be nice to get some race challenge running. If I remember correctly, there were only one or two entries in race challenge on old forums. May need separate divisions "flying" and "no jets, no propellers, no mass drives".
ACL as it is now still has a lot of things to try:
Swarms - we still have not seen much teamwork. Ant seems to only have friendly fire protection in targeting system. Same for Nest's missiles.
Unguided grenade weapons - Catapults. Rockets. Spin a grenade, roll it forward, wait, detonate, laser-ram the survivors.
Grabbing devices on laser bots - stick some thin parts into opponents armor. Maybe try to lift his front to attack bottom. Attach a grabber with jet and run jet at full thrust to get opponent out of the map? Maybe not the most practical thing to do but would be fun to look at.
Planes.
Non-plasma hovers - why is plasma the only weapon ever used in the air? Most bots are vulnerable to direct top-down laser attack. Automated bombing is possible in controlled environment, somebody tried it on old forum.
I think the main limit of ACL is that automated combat bots are hard to build and require much time.