Well, he's not as flat footed as he used to be, but I don't see anything vastly different in terms of his offense and defensive striking.
Henry likes his fighters to throw feints and keeping their head off the centre line - but I've read the myths about him having a glass chin, but when he does get punched, he almost freezes and reverts back to keeping his distance, resetting and throwing the leg kicks.
His striking when it comes to setting up and throwing punches is not that particularly noticeable. But I do feel he panics a little bit and goes back to his old stance.
That's the way I see it. If his 'entire style has evolved' which is a bit of a blanket comment, I'd be curious to read your take on his evolving.
You touched on it with the flat-footedness, but it's more his movement. When you rewatch his fights with guys like Jamie Varner and Terry Etim, it is amazing how awful he was at escaping the pocket. He was very uncomfortable moving backwards and taking steps straight back cost him big against Varner. He struck a lot like Germain De Randamie in the sense that he took the center and look to land and counter with kicks but was present to be countered himself because he refused to move and when he did, it was straight back. Now announcers blow his footwork left and right because it really is a very improved facet of his game and a game changer in his career.
Fast foward to his fights with Bobby Green, Tony Ferguson (even in defeat), Beneil Dariush, and Gilbert Melendez. All of these guys strategized to pressure the living shit out of him. All of these guys are better and more effective at it than Jamie Varner (even Bobby Green who had yet to lose in the UFC and confidence was sky high). Barboza executed a vastly different style by choosing to fight off the back foot. Whereas early in his UFC career, Barboza would have to have you go backwards or be stationary to land his kicks (Cowboy still has that problem), now he is one of the best in the world at landing those kicks as counters while he is sliding just out of range That is one of his most marked improvements.
In addition to using movement to avoid strikes, you can also see how good he's become at using footwork to avoid the clinch altogether. His fights against Danny Castillo elucidated how bad he was at giving his opponent the clinch, nearly at will, and he relied on his strength which allowed Danny to mix it up by throwing bombs and level changes together. When you watch Barboza's fights with Dariush and Ferguson, who are both pressure fighters (you can really see how good Dariush is at initiating clinch by watching his fight with Magamedov who is no stranger to the clinch and using footwork himself), you can see how he allowed his movement to not only avoid getting taken down, but he denied those guys the chance to even clinch with him, especially Dariush (ferguson got a hold of him by flying kneebar).
In addition, his boxing defense has gotten loads better. He was getting tagged back in the day by far more inferior strikers like Rafaello Olivera, and he even ate some bombs (albeit never getting hurt) from guys like Lucas Martins. Compare the to the Barboza who dismantled Anthony Pettis without getting his clean the entire fight. A lot of guys will say "oh Pettis is on the downward turn" which is fair, but when Edson fought him, Pettis had never been outstruck purely on the feet and he came in that fight brimming with confidence. For Edson, that was the biggest step up of his career and he showed his levels had increased significantly since the days of close fights with Njokuani and such.
This article does a good job explaining these in detail. Jack Slack has also written about Barboza being "a completely different fighter" than the guy that lost to Cerrone and came straight forward and back.
https://www.bloodyelbow.com/2016/4/...nthony-pettis-technique-strategy-jab-kick-leg