How does a clan even survive when the Khan is an elemental? Doesn't the first person to challenge him to a trial just stomp him? Did they even think this through, beyond "hey, wouldn't this be cool for a change?"
The challenges are balanced to be fair. In one of the books, Phelen Kell/Ward was fighting for the Ward Bloodname and fought elementals twice, once with equipment and once without. (If I'm remembering books I read more then a decade ago correctly.)
Without, they fought in a zero-G environment, if I recall, which balanced all the sheer edges the Elemental had over him (mass, size, trained infantry trooper etc.)
Armored, he was given a very light mech and they fought in a close in environment lousy with radiation and magnetic anomolies, which let the elemental close with his mech and climb on, negating most of the mech's advantages.
It's also really, really hard to stomp an elemental before they jump onto your mech and start cutting their way in.
But that was always the case. The only reason the clans were originally a threat was because the Inner sphere wasn't united and not only fought against eachother... but were also extremely uncoordinated.
Also true, but also the Inner Sphere were still a year or two away from a technology renissance from rediscovered Star League memory cores that ComStar hadn't managed to destroy in time. At the start of the invasion, everything clan built was 50%-100% better - lighter, stronger, longer ranged, produced less heat and cooled better. Once Star League equipment started going back into production and they started reverse engineering clan equipment, it really did become a matter of people getting their acts together and getting nations spanning a quarter of the galaxy each all pointed in the correct direction. (Liao didn't count at the start. >_>)