Often, fantasy baseball and actual, real-life Major League Baseball run antithetical to each other in key (some would say foundational) ways - a simple example would be the role of defense, which is non-existent in most rational fantasy leagues, but can have a serious effect on a player's value (see: Braun, Ryan or Jeter, Derek) to a real-life team.
One of the often-ignored elements of baseball, from a media/fan perspective, is the business side of the game and its effects on the baseball operations side of things. Now, people like Maury Brown do a great job of breaking down the actual economics of the game beyond the playing field - that's not entirely the scope of our discussion here. However, the economic side plays a strong role in on-field strategy when it comes to the marginal cost of player retention, arbitrage opportunities, and projecting the economic landscape of MLB years down the road.
Us fantasy GMs carry only a small fraction of this responsibility, mostly related to keeper leagues or auction leagues, where projecting future performance versus your own likelihood of success this season can influence trades and player acquisitions. However, the real-world economics of baseball can have Chernobyl-level disastrous effects on fantasy teams if idiots like me are unaware.
One great example comes in Evan Longoria (sub req), the Rays' superprospect that BP projects to put up a .267/.339/.460 line with 25 HRs should he start at 3B for Tampa Bay's version of the Travolta sudden resurgence from the abyss. Just for comparison's sake, that .799 OPS would be slightly better than the 2007 numbers posted by stalwarts like Ryan Zimmerman and Casey Blake, and in the ballpark of Adrian Beltre and Chone Figgins. At age 22.
This would be a pretty sound upgrade for the Rays, who could then move Aki Iwamura to 2B, and count on a year's worth of improvement in their pitching staff and OF to drive them toward (if not above) .500. However, Evan Longoria will not be starting the season on my fantasy bench - he'll be starting it in Durham, playing AAA, the same place he tossed up a .900 OPS as a 21 year old last year (caveat: <200 PAs).
This is a great move for the Rays, as Longoria's service clock will not start, and the Rays can still call him in up in June and get ~400 ABs from their 3B of the future while likely hovering around the fringes of the Wild Card race. The Devil Rays will effectively gain an extra year of arbitration control, going through his age-29 year instead of 28.
Jared Saltalamacchia finds himself in a similar position - he's projected by PECOTA for a decent .269/.337/.446 line at age 23, which would fall right between the 2007 marks by Brian McCann and Jason Varitek. This would also top Gerald Laird's career line by over 100 points of OPS. However, Salty also found his way off my starting lineup, and onto a bus heading for Oklahoma City. This was under the guise of "catching every day" - but given the lack of information we have over catchers' defense, this is most likely a way of gaining an extra year of service time as well.
To be honest, these moves make perfect sense - an extra year later is much more important than the MLB-level development time now, as the next two years will not result in the next (first?) great Rays or Rangers teams. However, these two players, by virtue of being the best available option for these teams, made it well up my draft board and represented a good chance for me to make ground late in the double-digit rounds.
However, this arbitrage comes with risk (weird, huh) - the risk that the teams will actually do the right thing, and not put the best squad on the field every day. Unfortunately, teams are getting smarter (exception: Gordon, Alex) - and risks are getting bigger. This is how you wind up starting Mike Napoli behind the plate - and it's not a good feeling. Not good at all.