WR's Subbing as CBs

I know I have had at least 2 games where somehow Shipley (WR) manages to sneak in as a CB. I know one time I was called out with them thinking I had purposefully subbed him in, but believe me there is no reason i want that slow piece out there defending real WRs. I checked my depth chart multiple times and he is at the bottom of it seeing as he is a 17 overall CB. So does anyone know why madden does this or how to make it not happen?

this happens when all your db's are fatigued. the cpu resort to subbing anyone they can. i've even ended up with te's as my dime backs. there is nothing you can do about it

alright that is what i was thinking but it just seems wierd that it would choose the worst option possible. but I guess at least its nothing im screwing up

Also AI sometimes skips your starting wr's so even if he is sucky after the backup safeties if you only have 4 or 5 cbs he might get thrown in there

bc say ur cbs get fatigued like they do and u have a wr go into the cb postion to where ur wr is like devin hester, or ur wr with speed and that can catch... i have had a couple games in other franchises they sub in like ted ginn jr.. and i had an pick 6 with him.. it was funny... i was like thats awesome..