[garry1221]

1 year of service time is accrued 172 days. A season is 187 days. This comes out to approx 92% of the year. If you want real-ish time frames, I'd go as low as 90% of the year. I'd use this as a service time baseline.

Rookie eligibility is defined as 130 AB, 50 IP, or 45 days on the active roster. 130 AB is 33 - 44 full games started and not subbed out. (I est. 3-4 AB/game)
Rookie eligible math:
Tweak the math as needed, but here goes:
Days Active: Season length (days) * .24 = X
ABs: X * 2.89 = y
IP: # of games(not days) * .31 = z
Based on RL:
Days: 45/187 = 0.2406
ABs: 45(days) * 2.89 = 130.05
IP: 50/162 = 0.3086

When will a player lose prospect status? I'd use rookie eligibility or 26/27 yrs old, whichever comes 1st. While technically prospects, if a player plateaus developmentally before reaching the bigs and is in his later 20s, he becomes another minor leaguer who couldnt cut it. I almost said 25 years, but I'm giving college kids a good 3 or 4 years before giving up on them.