True. However, the criticisms of Diefenbaker tended to come from the 'blues' or 'high' Tories. A split in visions was grounded in the very roots of the party (Sir John A. being a 'red' Tory). 

And then there is the late George Grant in his powerful polemic, "Lament for a Nation" (1965), who essentially argued Diefenbaker was the last Canadian and conservative Prime Minister. 

Following Grant's logic, Stanfield represented a seismic shift in the party toward economic liberalism with the final nail being the election of Brian Mulroney who abandoned Canadian conservatism with the FTA.