Walt is out due to a difference of opinion with ownership over organizational philosophy, i.e., stat driven player development emphasis v. veteran ball club that primarily uses the farm system as an acquisition tool for vets. Yeah, there was the power struggle / personality conflict but, at bottom, my view is that the Walt camp had a different opinion of how to build the team going forward than that espoused by ownership. Walt's protege Bruce Manno is also out.
Now that DeWitt has thrown down the glove and unequivocally stated the organization's philosophy going forward, does the Dave Duncan pitch to contact philosophy still hold? It's an important question because Duncan is still under contract for next year. In years past, Duncan stood in the way of bringing a pitcher to the big club unless he had a sinker of some sort in his repetroir. The pitch to contact philosophy was clearly entrenched throughout the Cards minor league system. ElBirdo's interview with Adam Ottavino made this pretty clear if one need more evidence than statements from D. Duncan himself and Dyar Miller.
My personal opinion is that pitch to contact is a reclamation philosophy for vets who no longer have the stuff to be strikeout pitchers. Younger pitchers with strikeout stuff should not be force fed the pitch to contact mantra. It lessens their aggressiveness with hitters and fundamentally changes the way they approach hitters. For player development, enhance what the pitcher brings to the table rather than forcing all starters into the two seam, pitch to contact box.
Bottom line: I'd don't see how Duncan comes back if he is told his way of doing things no longer applies to the minor league system. Also, I don't see how the Cardinals really commit to player development 100% without chucking the pitch to contact mantra. Dave Duncan has to go which means Tony has to go.