The principle take-away from the 2012 MLB CBA policies implemented is that social governance is highly centralized. These very policies set forth by Major League Baseball are "law of the land." Meanwhile, ballclubs themselves are restricted from creating social policies in contradiction with MLB. Additionally, punishment can be lain on a player via the Commisioner Office directly OR by their respective baseball club (punishments may not be handed down by both organizations for a player's violation of policy... simply put, one or the other).
*Note: All 4 of the following policies can be found on page 254 of the 2012-2016 Major League Baseball Collective Bargaining Agreement.
Expanding upon the 2012 MLB Collective Bargaining Agreement, a memorandum released by Major League Baseball in March 2012 set forth greater detail regarding social media policy.
Craig Calcaterra of Hardball Talk does an exemplary job of summarizing the "don'ts" of this memorandum (2012 MLB Social Media Policy):
"The policy itself is more of a legal document, but it basically consists of a list of ten prohibitions:While these control measures are fairly straightforward and common sense, the very fact that Major League Baseball has set guidelines to govern player social behavior represents an acceptance of "new media." Furthermore, it goes without saying that Major League Baseball recognizes the crucial role that social media plays in the lives of the young, a demographic that MLB must accommodate in order to remain sustainable and popular.
- Players can’t make what can be construed as official club or league statements without permission;
- Players can’t use copyrighted team logos and stuff without permission or tweet confidential or private information about teams or players, their families, etc.;
- Players can’t link to any MLB website or platform from social media without permission;
- No tweets condoning or appearing to condone the use of substances on the MLB banned drug list (which is everything but booze, right?);
- No ripping umpires or questioning their integrity;
- No racial, sexist, homophobic, anti-religious, etc. etc. content;
- No harassment or threats of violence;
- Nothing sexually explicit;
- Nothing otherwise illegal."