If I need a player as CB, his Bpos grows faster if I use them as CB for defense and CB for Special Teams?

No

No

I have not seen anything that would indicate that playing a player at CB or special teams CB would affect BPOS any differently. Same for K and P. In other words, it doesn't matter which position you play them at, they should gain BPOS at the same rate.

PHI 21 wrote: I have not seen anything that would indicate that playing a player at CB or special teams CB would affect BPOS any differently. Same for K and P. In other words, it doesn't matter which position you play them at, they should gain BPOS at the same rate.