The problem IMO is that this "anybody can play anywhere attitude" which is clearly prevalent in the current game IS promoted by sabre-matricians because of course defense does not matter and a bunt in all cases is a wasted out. Then they get to wait for the actual numbers to come in on a player in a defensive position when in fact all it would take in Mookie's case and in most cases with most players is a pair of baseball eyes to see that he simply does not read the ball well from CF. You can see it in how he positions himself out there and in how he reacts to the batted ball from out there. You don't need numbers to stack up to figure that out. You just need a pair of eyes.
If a player can't read the baseball from CF he is doomed as a CF. Its just that simple. Never mind the other characteristics of a CF that a player simply may not posess. Corner OFers do not rely as much on their reads because it is soooooo much easier to read the batted baseball from Corner OF than it is from CF. So if we bothered to look, we could have seen that CF was going to be a problem for Mookie from the first step he took out to his position in CF and from the very first step he took toward a batted ball from that position.
You can teach an OF player what base to throw to, how to back up his brother OFers, where he should look to pick up his cut off men, how to effectively call for the ball, how to successfully cut off the ball hit in the hole that has come to earth, how to turn and shield his eyes from the sun or lights and still be in position to catch and throw the darned thing. You can even teach him how to take more direct routes to catch the baseball in the first place. You can't teach him how to read the batted ball in the air and that happens to be the very talent that defines the CFer. You can't teach a strong arm though you can refine an inherently strong arm. Those are talents he either has or he does not have, just as you cannot teach hand eye coordination from the batter's box.
The reason so many of us have stated regularly that we needed to be patient with Devers in the field is because you could literally see the natural talent to play 3rd base oozing out of him if you knew how to look for it. Didn't need some number which would have suggested just the opposite in his case. I have often said here that if Devers does not improve his footwork he will never even be an average 3rd baseman. That was not because he didn't have the physical talent to improve his footwork. It was simply ignored in his development as a player. But the physical talent was always there as evidenced if nothing else by his pre-pitch posture ahead of that grass-cutter he gobbled up at 3rd last night and the way he gobbled it up....on his toes, glove down, two hands. I don't want to remember how Rafi would have gone after that ball even a year ago. I have a weak stomach.