I was thinking along those lines also. What made me doubt it was that I've went through three (now at the beginning of four) careers so far and all of the fighters I've created have had the same basic "boxer" stance even though they all haven't been boxers. Maybe the style of the fighters I've picked just happen to have the same stances?
I'm specifically looking for the stance that has the guys arms relaxed by his side. I'm going to start another career and see if I can find a different stance. If not, thats kind of an oversight (not a huge one in the big scheme of things) on the devs behalf. Every little thing serves to spice up the career mode, which right now really isn't that deep….fun and a good game…..but really lacking depth on the career side of things, could've at least used some different visual styles.