The mechanical way that the Tabletop Game Battletech plays (ie, mechs are relatively durable until they aren't, and you roll goddamn chance cubes which flout the suggestion opf probability) means that it is actually shockingly common, especially in ye olden second edition, for a game to wind up with a bunch of nigh-victorious mechs surrounding a single final opponent, and - despite having almost no rational probability of missing - having to chase them and shoot for rounds after round after round to finish them off: Missing, stripping every stupid point of armor off non vital locations, and alpha strike after alpha strike refusing to generate any fatal critical hits.
In fact it is so fundamentally common to the way that Battletech played out that there was a canonical 'urban legend' in an early novel, written by none other than Michael Stackpoole. While the wiki (and in some cases, the fandom) will get in a tizzy over the "one supernatural thing in Battletech" it's extremely obvious to anyone who has played the wargame that it's just a thing that happens with alarming regularity in the game.
In the end, Kurita feigned the failure of his right PPC, then surprisingly used it to shoot off the Archer's right arm. Kell's critically damaged 'Mech toppled to its knees right in front of Kurita's Warhammer who then fired all weapons at Kell's Archer ("Alpha strike") at point-blank range, but miraculously missed with each and every weapon although Kell did not even move. Conversely, Kell fired his long-range missile launchers. The missiles failed to arm due to the very short range; their impact did crack open the canopy of Kurita's 'Mech, however. Kurita fired all his weapons once more, only to completely miss Kell again.
This clearly isn't an irrational supernatural miracle it's just a normal day of terrible RNG in a game of Battletech honestly.
Why in the fuck would it need an escort, this is already a fucking armor column not a convoy. These are the most deadly vehicles in the entire universe of Battletech.
They certainly didn't need 200 tons of mechs added, thanks you asshole RNG mission creator.
Ugh this fucking game