juan
Yes. As soon as Kopech recovers from the surgery and is healthy, they can activate him and then reassign him to the minors to try to delay his free agency date. He was credited with 41 days of service time for 2018. So he needs 50+ days of minor league non-rehab assignment in the next few years to delay his potential free agency by a year. IIRC, this must be done before a player accumulates 3 full years of MLB service time as a player with 3 years of service time cannot be optioned to the minors without his permission. That's in the current MLB CBA which expires after the 2021 season.
http://www.mlbplayers.com/pdf9/5450407.pdf
I do appreciate all these things that you know or know how to look up Andy. I have a hard time keeping up on some of them. Good question however by Juan too.