Pro: Chaim Bloom has consistently built up top farm systems
Bloom had some very odd tasks given to him right off the bat during his time in Boston. It's hard to expect an entire organization to become like the Tampa Bay Rays' overnight, especially when they were also asking him to cut payroll significantly, trade a future Hall of Famer in his prime, and find a way to keep winning in the midst of it. Oh, and the pandemic happened just months into his leadership.
Still, Bloom was able to turn the Red Sox's farm system into one of the better in all of baseball during his tenure, as names like Marcelo Mayer, Roman Anthony, Kyle Teel, and Ceddanne Rafaela were all top prospects that are supposed to be a major part of the Red Sox's new core moving forward. As I mentioned earlier as well, the Rays consistently had top farm systems when Bloom was around as well.
Bloom is highly regarded for his player development philosophies, but he also has a knack for identifying talent and bringing it into the organization. The Cardinals have done well drafting under Randy Flores' leadership, but adding Bloom to the mix could help the Cardinals make more targeted risks in their drafting moving forward.
Building a farm system is not just about the players you pick though, it is about helping them realize their potential. Bloom has already been tasked with, and helped the Cardinals make, multiple changes to how they approach player development, and he'll continue to speak into more changes to come beginning this offseason. I don't think it is a coincidence that the same year that he comes in and makes some changes, we have begun to see someone like Quinn Mathews make a huge leap and become a top pitching prospect in baseball, or that other arms in the Cardinals' system appear to be making strides along with him.
The Cardinals have struggled to hit on their prospects in recent years, but Bloom's track record would at least indicate greater success in that area in the future.