This is a personal view on this subject - just a comment I was trying to make to Alex Hall's article on Brandon Moss, which evolved into the theory below . . .
There are two aspects of Moss' performance in 2013 that trouble me:
1) He would be more valuable as a homerun hitter, as a 5th bat in the lineup. Honestly, I was hoping for that this year, regardless of regression features.
2) I was also hoping that, being one of the older players on the team, he could become a leader of sorts in the clubhouse. However, that does not seem to be happening - whether because he feels concerned about his own performance, or whether because of some outside worries.
The A's give currently a "disjointed" feeling, as if they are not a TEAM, but an assortment of players with individual worries to solve. I hope I am wrong, but I do not perceive the "lightness of being" that permeated the team in 2012. And, without that "lightness", the A's are just another group of players, assembled by management and dressed in the same uniform. In Moss' case, having introduced himself as a standout homerun hitting, middle of the order guy, he is an integral part of the "team" feeling on the A's. He is an "authority figure", just like Cespedes (even if Cespedes cannot converse freely with his teammates); therefore, these two players have a tremendous psychological impact on the other players. Among them, Donaldson, Reddick, and Crisp are the only ones who have a comparable "image weight."
Therefore, we have that of the key (in authority and run-producing performance) five players at this time; only Donaldson - and possibly Crisp - are being productive as hoped for. Two out of five is not enough to keep the team battling for a first spot in the Division! Taking into account that everybody goes through periodic slumps, the roster was constructed in Billy Beane's mind to withstand, maybe, two out of the five being in a slump. That is, three of these five key players would be expected to be in good form at any given time. And I am not ignoring the other players, since that they are not the figures to impose in the clubhouse, and are a "mixed bag" - like Lowrie with the double image of a good bat and relatively poor D, or Smith with the dubious image of a sometimes fielding DH.
The A's cannot afford to have Cespedes, Reddick, and Moss not producing up to optimistic expectations. Statistics being descriptive (in a PAST tense), it is somewhat irrelevant whether these players should or should not regress to a mean. These are, except for Crisp, young men, who do not have years of track record behind them; if they are still improving and learning, statistics from the previous one or two years should not be the absolute determining factor. So, as in any organization, blame for faulty performance lies with "management" - in our case, Melvin and the coaching staff - to figure out what is bothering these players, for them to produce a less-than-expected performance. And platitudes about it being too early, or not worrying about Cespedes' performance, or not observing Reddick's being influenced by his sore wrist, or not helping Moss to cover the holes in his swing, are just that, platitudes to avoid disturbing the pond.
Management's job is often to "keep peace in the family," when going is good. However, the real challenge comes when "going gets rough" - that is when subtle psychological fine-tuning is needed, particularly with primadonnas - which baseball players are, being part of an entertainment industry (just like so many Hollywood stars and starlets). That is the reason for the "Shake Up the Roster" cry, to generate some passion among these starlets, and have them performing as stars under suitable emotional stress. After all, we know that a certain amount of stress is needed to feel truly alive and challenged in life!