problem with pass blitz assignement

hi,
I'm trying to make my CB 'pass blitz' from his cover position (inside shade) but instead of being close to his receiver, he is placed right in between the DE and DT. However, he is well positionned if he's in the 'rush blitz' mode. On the practice field, you can drag a player before the ball is snapped: so I did correct  his position and it does make quite a difference (between pass and rush blitz mode). But on the next play and/or on the chalkboard, my CB is 'stuffed' again between the big guys. Does any one have a clue?
Félix