It's a very good question Curtains.
I think we can all agree that it took us a long time to adapt to the way PW is setting us up / wants us to play.
Whilst the football may not be great, our results over the last dozen games or so has been bloody impressive, and if it continues, we will be there or thereabouts come the end of the season. We do have some cover in most areas, especially when everyone is fit.
Bringing new players in might be beneficial, but how long might it take them to get up to speed with the PW way? Furthermore, what impact might it have on the moral of current players in that position?
Losing players would be a blow, even if it generated money to bring in new faces, partly for the above reasons.
Finally, PW stated some time ago that he wanted to do any transfer business early in the window. Would any transactions now not smack of desperation?
I'd stick with what we have and keep the faith.