Alright, some notes:
First of al the game has a decent overall feel to it when in the middle of it. Its basic but has the feel of the physics of the punches mattering a bit.
That said, the tuning of the game is not ideal atm. I can spend *minutes* in a match just waiting to move to or from corners, waiting for my opponent to recover from their concussion, and in other little situational bleeds.
Additionally, I was able to beat up to hard difficulty with no real tactics or concern for what my opponent was doing, or what might be effective -I simply just wailed on them with hooks until they went down, pacing them out at the rate of my stamina consumption (once I realized low meant slower regen as well). I did not block, I didnt even hold the controler so I might be able to.
Your hardest AI has obviously got to be better than this, and I understand AI can be difficult, but if this means you have to make it cheat *a little*, its probably worth it. Part of the joy of this sort of game is the progression of skill, and not needing any is probably a bit too light
Additionally, as the movement is flat - not having the ability to lunge or weave or mete it out with any obvious extremity, the skill ceiling is naturally going to be a bit lower here. Its likely worth it to have your first movement in a direction be a bit faster and a bit more stamina consuming - to give the option of repeated tap movement for higher speed, and to allow a bit more varied skill expression.
Finally WRT staying down, its likely going to be worth it to make it harder based around the difference in your conditions. If I am above 90, and they are at 14 max head condition... maybe just stay down my guy. It will save me 30 seconds, and save the virtual opponent another needless concussion.
I do appreciate the work you are doing on this sort of thing, but I do think its going to take a bit more physical interaction and variation to really make it pop.