the anatomical structure of his body doesn't seem correct to me. his posture drives question such as how the fuck can shorts hang so low yet not expose anything nor show any detail of slipping off or whatever they're doing
seriously the shorts are unnecessarily low (unless if thats what youre going for which is cool but at least show some detail as to why they're so low)
i go back to his posture, and looking at it as if he's a boxer it doesnt seem like a position you'd find one in. his legs freak me out too b/cause in my image they can be going either direction since i cant see his knees or anything
the gloves could also use some help too
anyways, my advice would be to try drawing reference poses for this char, and get used to drawing him in whatever outfits you intend on putting him in, be it boxing gloves or low shorts.