GS, Mace/Torch is weak on that map, and might be part of your problem. Like Lukeee said, Sword/Shield is awesome on that map (sword 2 is wildly useful if you get controlled off of the point). If you don’t like the MH Sword, Scepter/Shield, Hammer can be effective too (Scepter root + Banish and a well placed Ring of Warding is an auto decap if the opponent can’t get stability up or teleport). The bottom line is that mid node is far more defensible by knock backs than any other mechanic. The more you blow opponents down the ramps on the sides the better. Having a team mate there that can knock pesky ranged DPS off the catwalks (out the windows) is handy too (again, knockbacks).
Practice dodging treb shots in a hot join server with a friend. The animation doesn’t really synch with the correct dodge timing, so you do have to learn it a bit. Also pay attention to the timing of the audio ques “Trebuchet!”, “Incoming” and work on timing blind dodges (when you can’t see the shot incoming) in combat (probably the hardest thing to master as far as the treb is concerned).
Have a plan going into the match for opponent treb control. You need a strong direct damage source to take it out ASAP. If your team comp has an ele, then FGS is a super fast way to eliminate treb. Thieves can get to and disable the treb quickly from anywhere on the map. Necro Golem can chunk it pretty good with charge, but a condi necro sucks at direct damage otherwise. Most Warrior builds can handle opponent treb pretty efficiently if you have one on the team.
For your treb you can put a few strategies in place before the match. In low rated matches a single player that can run the treb effectively can hard carry the map (good teams don’t get beat by this, but you can 500-200 bad teams pretty reliably if you just have a good treb operator). The treb op should be a solid 1v1 build with some mobility, because he is likely to get forced into a 1v1 and he needs to get around the map fast when the treb gets disabled. Discretion is usually the better part of valor for a treb op. An opponent well suited for treb disabling will be able to knock out the treb whether you try to stop him or not, so recognize quickly if he is trying to 1v1 you or trying to knock off the treb and if he is trying to kill the treb, then abandon it and support a node that is being fought on while he wastes time on the treb. Repair it when an opportunity arises, but prioritize holding 2 nodes first. If you know your opponents are solid it can be good strategy to ignore your treb until a critical point in the match (they probably won’t waste time to take it out if you aren’t using it). If you can catch a 3v2 or 3v4 at mid with the treb and flip the result in your team’s favor with the treb it can be match defining.
With all push back options it the best prof for guarding middle point. I was facing guardian today and he was on that platform for a minute without me even touching him.