Personally? I've only ever played in stand-up games that were single-battle "Last Man Standing" or "achieve X objective". Clashing forces have been rather well balanced (only once did I play an ad-hoc game where I didn't have any Lance cohesion; once I learned the rules, it never happened again).
As for one-sided battles? Most recent one I was in happened March 7th at Arcticon (Valpraiso, Indiana). First event was a 3-man, 250 PV Alpha Strike "Free-For-All" on a 4x4 table full of terrain.
- Corner 4 (me), 1 mixed Star [Indirect Fire] with Summoner, Madcat, Vulture, Dasher, and 5 Gorgon Protos; skills roughly 2/3
- Corner 3, Society Star w/ 2 Osteons, 2 Septicemia, and 1 Cephalus (all w/ Nova CEWS); skills roughly 4/5 to make the cut-off
- Corner 2, mixed Lance (1 Shogun, Centurion, Wolfhound IIC, Jenner); Skills all 0
The Inner Sphere Lance never missed - they hit every Target Number. However, except for the Shogun ("C" variant that does 7 damage at Short and Medium ranges) their mechs couldn't do more than 3 damage at a time. AND that player was focused entirely on the Society mechs, earning the first kill by taking down a Septicemia, and, later, the other one. (2 kills)
The Society mechs were the beefiest on the boards - lots of armor, crit resist, etc - but their pilots were grossly underskilled. My best guess was that their Accuracy was a meager 20~25%.
Even with the Nova CEWS, the lowest TNs for that player was an 8 (4 skill + 2 range + 2 TMMs on average, or 5 skill + 3 TMM). With it's 2 favorable c3 networks, the Society player was able to split fire between the two lances, but only managed to kill the Centurion and Jenner of the Inner Sphere Lance (2 kills)
The Clan Star was there to essentially mop up what was left. After the Cephalus underestimated the jumping potential of the Summoner, fatally ignoring the Protomechs (previous damage allowed two Gorgons to tear it apart and kill it). The Dasher - moving from cover to cover - devastated the Shogun from behind before giving chase to a fleeing Wolfhound. The first Osteon made the mistake of closing to range on the Summoner as it moved to away engage the Shogun. It receiving concentrated fire - both direct and indirect - that crippled the exposed mech. Once the Ceph was neutralized, the Osteon's began to withdraw but fell beneath the Vulture's talons.
The Shogun and surviving Osteon charged one another, only to be flanked by the Clan forces. The Summoner swooped in and tore out the rest of the Shogun's rear, an ammo explosion sending the mech to the dirt even as the Dasher finished off the Wolfhound; the Osteon took more critical damage that crippled it just as it's twin had.
In the end, it was 9 units vs 1 crippled, armor-less Osteon.