Starting this week MLB teams can call all prospects up without putting them on the fast track to free agency. If a prospect’s big league service clock starts after today, he’ll be under team control through at least 2018.
Today represents the 20th day of the minor league season by my count. This means prospects on 40-man rosters such as Trevor Bauer, Bryce Harper and Danny Hultzen will have spent the requisite 20 days on optional assignments following today. Even if their teams call them up tomorrow for the remainder of the MLB season, they will accrue a maximum of 162 days of service -- short of the 172 days required for a full year.
For the past few days it's been safe for teams to call up prospects not currently on the 40-man roster. Players such as Brett Jackson and Shelby Miller didn’t have to spend 20 days on an optional assignment, they just had to spend enough time in the minor leagues to ensure that they’ll fall short of 172 days in the Majors in 2012.
As always, it’s important to note that service time is just one element of a team's decision-making process and that a substantial proportion of top prospects get optioned to the minor leagues early in their careers. The player's readiness and the team's needs generally trump service time considerations. But service time matters a great deal for elite young players.
Teams wishing to prevent their prospects from obtaining super two status following the 2014 season can keep prospects in the minor leagues until late June. This should ensure that the players are only arbitration eligible three times.
Here's a complete look at the timeline for calling up top prospects.