PC files and console files are different and have different values in different areas. These guys are editing the PC files and then converting them to the consoles.
Problems can occur because a PC file might be calling on another file that the console versions don't have etc... Lots of problems can occur.
All I know is that there have been a few people with problems. I'm one of them. I know that when I used these rosters, my batting dropped off. After using the default rosters I was fine. I tried this playing 4 games. 2 with the rosters, 2 without. Same teams, ballpark, wind, pitchers, everything... Something seemed off to me.