He has also promised supporters the team they watch next season will be a "different animal".
Westley was appointed as Phil Brown's successor in January but only managed three victories before the end of the season amid constant reports of internal strife at Deepdale.
However, the man who led Stevenage to back-to-back promotions before heading north remains convinced he will be successful after implementing significant changes this summer.
"Since I've come in, I've kept asking people to do things in a certain way and they haven't done it," he told the Lancashire Evening Post. "You check that they understand what they've been asked, yet they still don't play in the way you want.
"Managers like Phil Brown and Darren Ferguson have been very successful and won promotions at other clubs - so have I. There is a point in time I think when you have to say, 'Maybe it isn't all these managers and maybe the group has got something lacking in it'.
"When we change the group, we will put ourselves in a position where the best in the group are forced to thrive and kick on. I'm confident I will put a side together which will be a very different animal."
