One thing I've discovered since getting into this again is that there is such a thing as TOO MUCH tonnage on your team, especially trying to survive the Hard and Suicidal difficulties. If you have 800 tons of mechs, the enemy is going to have even more, and while efficient mech designs and play strategies can defeat them, they are likely to unload enough ordinance focus fired onto a single mech of yours that the engine explodes or the pilot is killed before even getting a chance to surrender, eject, eject ammo, etc. Keeping your team weight low can prevent the one-round kills because the enemy won't have enough firepower to wipe one mech out before you can do anything about it.