[I_Tyler_Durden_I]

If it is that they were able to do, it is close to be called a joke. Changing positions in a custom roster file should no problem at all. There is no problem at al, because what can you exploit at this time? Nothing! After starting your CC it could be a bigger thing to do. But to be honest, I do not see that big of a problem. Changing an T to C shouldn't change the goals that much. Same thing with DE and OLB. The other thing they mentioned was productivity. As I know, this value is zero from the start of a players carrer and gets higher based on some stats. I guess different stats are rated higher then others (A DE is likely more productiv when his sack stats are high and a CB will be more productive if he has a lot of INTs). So if a player changes his position, take a look at his stats and recalculate the value based on the stats regarding his knew position.
I would say it is more a problem of how the code works (or does not work), than a design problem.