Do you follow kickboxing? Glory you could argue is sort the #1 organization right now (although OneFC now has some of the best fighters under contract like Giorgio Petrosyan and Marat Grigorian), but the sport doesn't really have 1 home since 2010 when K1 kind of died. So instead, I look at the opponents, not the organization. And Adesanya had some other bigger decent opponents like the ones I mentioned in the previous post. I watch a lot of MMA, but at least as much kickboxing as it's the first fighting sport I watched (and then learned). There's a lot of good kickboxers outside of Glory. Glory doesn't have that much capital and they don't really go after all the top talent out there. They do like 1 show a month at best.
Pereira is huge. He looks bigger than most LHWs. He looks like a small HW. The fact that he just moved to LHW doesn't change that fact. He looked bigger than Vakhitov in their fight. And he is also murking people.
You are 100% right that striking is a different ball game in MMA than it is in kickboxing. Most kickboxers are a lot more stationary and have a more upright and less wide stance. They throw a lot of combinations and keep their hands high. In MMA, glove size is different, clinching is different, takedowns are a complete gamechanger, you have a cage instead of a ring and elbows are allowed. I would argue though that Adesanya has adapted very well to MMA (obviously). You are making it seem like he just transitioned to MMA. He is outclassing top MMA guys with his elusive movements and striking. Comparing him to Saki is not really a good comparison. Saki has a different style and he didn't train a lot for MMA prior to coming to the UFC with his 0-1 MMA record. He failed to adapt. Because you are a good kickboxer indeed doesn't mean you'll be a good MMA fighter. But with Adesanya, we can see that he has been able to transition properly to MMA.
I believe Jan has a good shot at beating him, if he comes in win with a good gameplan. A lot of pressure and mixing striking with wrestling/grappling. Keep the fight close and dirty. Make it a hard fight with a lot of grappling exchanges and dirty boxing, on the cage wrestling. Don't allow Adesanya to find his range and feel comfortable. If Jan just goes into striking mode with Adesanya, he's not going to win. If he allows Adesanya to control range and strike from the outside, his only chance will be catching him with a big shot on a counter. And probably he won't be fast enough and lose the fight.