As far as I can see it, it's like this:
DJ Campbell - not happy at the Walkers, attitude problem which NP didn't like born out of frustration at not playing, so best to let him go and not infect the squad. He will not play for us again.
Sappleton - Not fulfilling the promise at all at present, but minds are not 100% made up so has been given time away to get experience.
Dickov & Hayles - Both way past their sell-by date could still do a job in this league off the bench (see Dickov Vrs Colchester) but by no means an acceptable option to partner lazy-bones Fryatt.
Chambers - NP likes a lot, pace and quality on the ball, however will not be blooded in in a pressure situation - NP would rather bring him on steadily. Arguably should have playued ahead of Dickov (who did little up front) at London Road however.