I'll Take Schuerholz
The correct answer to the question seems suprisingly easy, which is why I was shocked when Bradley wrote that Cox is more irreplaceable, and thus more valuable to the success of the Braves. Forgetting concrete evidence for a moment, the titles of the positions alone should provide a clue as to which job has more value to a team, but Bradley is intent on anointing Bobby Cox as a god and nothing will deter him from that pursuit.
Bradley's lone plank on which he built his shaky argument is the fact that Bobby Cox has sat on the bench for all of the Braves' fifteen straight NL East division titles, ignoring that Schuerholz has been the general manager for each of the fifteen titles. He also seems to think "one or two other GMs could have stitched together comparable rosters for the price Schuerholz has paid [but]...no other manager [than Bobby Cox] could have won division titles without them." This is utterly ridiculous.
To understand which job is more valuable, we must first examine the descriptions of what each position requires, starting first with the general manager. A general manager is responsible for overseeing the drafting of amateur players, acquiring free agents who will contribute meaningfully, trading for players (in-season and out-of-season), and making sure that the prospects he does trade away do not come back to haunt him. In this last regard, Schuerholz is a certifiable genius. Since he became the Braves GM, Schuerholz has traded away eighty-four prosects, and of those only six have managed 10 or more Wins Above Replacement Player in their careers.
Last year, especially, where the Braves won the NL East title with a roster full of rookies was more a testament to Schuerholz's ability to draft players who will quickly become major league players than it was to anything Cox did during the season.
As opposed to a general manager whose job performance is easy to measure by how well the players he acquires perform, a manager's ability is much harder to measure. The prevailing sentiment about the worth of a baseball manager is he only as valuable as his players, which just happen to be provided to him by the general manager. For the most part, there is no statistical evidence one can point to in order to say that is where the manager makes a difference in his team.
Throughout the history of baseball, no manager, including the Great Bobby Cox, has shown an ability to consistently outperform their team's projected record according to runs scored and allowed, help their teams by using sacrifice hits, intentional walks, or stolen bases, or improve a team's batting performance.
Now, Cox could have helped leaded the Braves to fourteen straight division titles by fostering an atmosphere in the clubhouse of expecting to win year in and year out, but if that was the case, then one must ask why he was unable to lead the Braves to division titles in his first tenure as Braves manager? Methinks the players doth make the difference.
In fact, the case can be made that Bobby Cox the general manager was more valuable to the Braves than Bobby Cox the manager. As the general manager, Cox was responsible for trading for John Smoltz and drafting players such as Chipper Jones, Kent Mercker, and Mike Stanton, who would later make Cox the manager seem like a managing savant.
Furthermore, it is Schuerholz who has been the one to win without Bobby Cox, winning four division titles and one World Series title with the Kansas City Royals. One cannot say the same about Cox winning consistently without Schuerholz.
So, which one, Cox or Schuerholz, seems more irreplaceable now? That's what I thought.