The TBC Newsletter
will keep you periodically up-to-date on what is happening at The Baseball Cube.
Signing bonuses can refer to drafted players and their draft signing bonuses from the drafting team or for undrafted free agents signing their first contract outside of the draft whether International or Domestic. The Bonus is used as a tool to entice the player to sign with the drafting team. Certain players, based on their situation, have more leverage and can command a higher signing bonus than others. High School players can go to College and so teams who want them to go Pro immediately can offer them a higher value than the suggested slot value. Juniors in College can go back to College for their Senior year. Freshmen and Sophomores in Junior college can advance to a 4-year school. About the only player class that has limited leverage is the College Senior who may not have much of a choice but to sign with their drafting team if they have any interest in going Pro.
Undrafted free agents will also receive a signing bonus from their signing team. In both cases (Drafted or Undrafted) teams have a salary cap for bonuses that they must adhere to.
TBC tries to track Signing Bonuses wherever possible. For drafted players, whatever is publicly declared, we should have. For undrafted, its one of those long-term projects that includes sporadic data based on availability. We try to dig and find bonuses wherever possible.
In both cases, I believe it is worth looking into the data products in the data store if you want a broad view of signing bonuses over time.