Re: Years of service and arbitration/free agency
The point that I see most often confused is that service time, for purposes of arbitration and free agency, is based on the number of days spent on the active roster. (I believe that 172 days is the baseline for a year of service time.) It is not a running clock from the first day spent on the active roster, although it works out the same if the player never goes back to the minors. Nor does a player get a year of service time just for being on the active roster at some point that season.
Let's say a player was called up on June 1, 2004 and spent 60 days on the active roster before being optioned back to the minors. He was on the active roster for 12 days in 2005 and 100 days in 2006, spending the rest of the time in the minor leagues. Following the 2006 season, he did not have three years of service time, even though he's been in the majors in three different seasons. He did not have two years of service time, even though his first callup was two-plus seasons ago. He has 172 days, and therefore exactly one year, of MLB service time.
Going back to the original point, unless you're the Yankees or Red Sox and money generally isn't an object when it comes to your roster, service time is a huge consideration. Players can only be controlled for so long, they can only be cheap for so long. It has to be managed intelligently.
Not all who wander are lost