Higgens it isn't all you.
Butters man...he actually don't look real bad as a textured mesh but actually 900 pollys is to low( yes I said to low..in all actually you can go to about 4k with so little dif you'd never know it in game speed). Theres not near enough horizontal lines, say in the thigh area or the forearm area...
When you try and rig something that don't bend well because your forcing polys to be dragged from one side of the elbow to the other you'll get big deformations when its animated.
I've heard people on this forum rave about box modeling....imma let ya in on a secret....less its a box.......don't box model. Boxes are fine for things like guns and soda machines but if you want to organic low poly model start out with 8 sided cylinders.....Yeah a cylinder....wanna know why? Because 8 sides will split either the figures arm or leg or body into 4 equal parts meaning you'll see four of the face columns from the front with a line right down the middle and 4 from the side with a line right down the middle. This makes shaping/texturing/rigging much easier. Don't use the optimize modifier(or whatever it's called in your modeling program to cut down on poly count)...thats whats given you all the long "shards" that extend from the crotch all the way to the knee.....
Kinda a after thought edit:
You really have to do a decent job on the modeling part man cause FPSC animations are over exagerated and clunky as heck. As a test put like Akio unarmed in a game then wile in the editor place the lil machine gun( I'll get flamed for that knowing all the gun buffs around here that know every model since ww2) uzi like gun in her hand so shes just holding it and wont attack. walk up to her and look at her hands....there a mess......the poor girls arms are jacked all outta shape. So even with as much detail as shes got she gets jacked......so 900 polys......pfft...look like a Picaso painting