Most retired players that I have met have rarely if ever had kind words for a former manager. One of the exceptions was Gil Hodges. He commanded the respect of his players, probably because he could break them in half.
I've had dinner with Tom Seaver a couple of times, and I asked him about the Mets great pitching staffs of the late 60's and early 70's. They all had the drop and drive deliveries where there back knees hit the mound as they used their legs for power. I asked him if that was taught in the Mets organization. He laughed at the notion. He told me that the organization taught them nothing. They came up with it on their own. Sadly, I think that is the story of player development in most organizations. The players learn to adapt or they perish. Period. I'm not saying that some teams aren't better at player development than others, but I am saying that it probably is much less important than people think. The most important ingredient is drafting, trading for and signing good talent.
On another topic, teams have become too dependent on numbers crunching today. I think it was Cafardo that pointed out that every team has a guy who can crunch the numbers today. It no longer provides a competitive advantage. In person scouting and expanding scouting departments and stocking them with top baseball people will provide the competitive advantage going forward. Scouting is expensive so the Red Sox should have a huge advantage moving forward.