I think it was Benson Henderson and the guys at MMA Lab who came up with the calf kick during a time when fighters were mostly doing thigh kicks.
You are correct on this, Benson was the first to implement calf kicks in the UFC (maybe not MMA as a whole, but at this point, it's hard to tell). It did take some time to catch on. I'd say he started that around 2015 and we can say that 2019 or 2020 was the first real start of widespread implementation of that kick.
here is my prediction for upcoming event .
Petr Yan vs Aljamain Sterling
Prediction : Petr Yan win by TKO / Decision or Aljamain Sterling win it by submission before R3
In Depth: Based on the last fight with Aldo , we can see that petr yan totally have the technique/knockout power for the knock out ,but for the challenger aljamain Sterling will either perform a submission early on [ I DONT THINK aljamain sterling able to TKO petr yan ] or it definitely will go in Petr Yan in later's round if he(petr yan) able to tired out Aljamain Sterling.
My Bet : Petr Yan win by TKO
Amanda Nunes vs Megan Anderson
Prediction : Amanda Nunes TKO Megan
In Depth : Will post afters
My Bet : Amanda Nunes win by TKO
The main event
Jan Błachowicz Vs Israel Adesanya
Prediction : Israel Adesanya by Decision
In Depth: Well , we all know that israel is totally a technical player , where he aim and shoot , and not spray and pray type. By this matchup i can see a similar match between Stipe Miocic (Israel) Vs Francis Ngannou(Jan Blachowciz) , Where Blachowciz will totally outplayed by Israel. But still we can't underestimate the Legendary Polish Power, if he caught Israel offguard , we will be see-ing a 1 shot KO from him.
Side notes : As Israel raising his weight from middle weight to Light heavyweight , we need to know that the previous records from Israel will not be accurate ( it will just for us to do some speculation ) , as we to know different weight class == different whole new fights , and we never know Israel gonna give up his agility ( speed ) for muscle.
My bet : Israel Adesanya by Decision
More update will be edited . ( Sorry english is not my main languages )
Yan/Sterling - Sterling has more to adapt to and change his style than Yan has to. There is a clear cut in what Sterlings and is good at and what he is not, wrestling is his bread and butter but he lacks in boxing and kicking, lanky with awkward movement trying to keep everything at distance,while Yan is the dominant striker lacking in the wrestling department compared to Sterling Yan's adaptiveness in the Aldo fight had me thinking that Sterling does not have the same fight capacity to adjust like that. However, there is always a chance STerling could catch Yan early and just tire him on the ground.
Nunes/Anderson - Only two women in this division, that says it all XD Anderson could, in the future, become a legit contender, but compared to Nunes, her experience, aggressiveness and all-around technique, especially on the ground (even tho most see her as a stand-up fighter), will be to much for Anderson and her really slow output.
Blachowicz/Adesanya - There is so much going on here that it's hard to write in one post. The gist of it is that I agree with your sentiment, we have to take into consideration that Adesanya is fighting out of his usual weight class (or at least a weight class he has occupied for some time now), but it's not just because Blachowitz has Polish power in his hands, that's just selling Jan short. He showed, great movement in the Reyes fight, his bodywork and the ability to defend Reyes counters. Adesanya will have to deal with Jan walking through his punches and bringing the fight to his face and will have to adapt more than Jan will for that matter alone, and that could, in theory, make Adesanya screw up his timing and his footwork. Maybe. The other thing is that Adesanya thrives from fighters that try to blitz him as Whittaker did, so that's something that Jan has to overcome, but again, that type of forward movement is something Jan does all the time. Hard one to call.
Final verdict: Yan, Nunes, Blachowicz