Most MMA fighters, Muay Thai Fighters and Kickboxers at a high level can't fight in the pocket. In Muay Thai and MMA the reality of the clinch kinda makes it less relevant, as the ability to stymie pocket fighters by clinching is just often so present and arguably from a biomechanical level clinching is more natural and effective than fighting the pocket. Beyond this, typically guys who fight in the pocket well need to have good footwork and defense as they usually need to be able to slip, close distance and maintain close space while also defending wrestling attempts and clinches, finding openings on the break and continuing to maintain that close space. It's harder to maintain space in MMA because the Octagons and Circles are more open and don't have the 4 corners to angle off and trap people as easily as well.
Beyond this, typical fighting from the pocket takes more skill...it requires greater shot selection, tight hooks and uppercut, combination punching, going high and low intelligently. But also it requires a greater amount of defense as you have to maintain a vulnerable position and know how to slip, block and roll and be able to seamlessly chain your defense and offense to be effective in that distance...which is even harder when you don't have the security of larger gloves to help block, deflect and dampen strikes. This just isn't a skillset that's widely represented in MMA yet, the shot selection, combination punching, intelligent pressuring, footwork, defensive prowess and blending it under fire etc. And for obvious reasons as I've said...the clinch, grappling, the openness of the space and of course since this is a very highly technical aspect of boxing and MMA focuses on so much more...it's naturally not going to be as nuanced in particular things that specialist sports are. Also in MMA, the main utilization of defense is simply space, guys are avoidant of maintaining a range at which both men can exchange in...downright uncomfortable. That's why when you even see a shorter fighter successfully close distance and get off a couple shots, he usually stupidly then gives up what he earned and backs off even if not being hit on his own accord due to instincts.
Good examples of pocket fighting is Sean Strickland and Gastelum giving Izzy fits standing. Ilia dropped Volk in the pocket with a 4 or 5 punch Combo and that's like the 3rd knockout of the sort in his career. Poirier has great punching in the pocket as well and really developed some good defense consider how chinny he used to he perceived as, with effective blocking. It's like a next step, you can't train fighters the same, a lot of these quicker, more compact fighters can expose the longer guys if only they are trained properly enough and early enough to become good at closing distance, footwork, necessary defense and offensive abilities in close range.
, I love how you pointed out how a four cornered ring compared to an Octagon can change so many aspects of a fight and how and the Octagon can nullify the need to fight in the pocket. So much of fighting is still ring craft. Your position and whether you are backed up or in the case of a ring cornered can completely change how effective various strikes are.
