I haven’t seen a single source that shows that he’s at 5-years service time. I’ve seen 4.1 a lot though. In MLB 172 days is a service year. Per Baseball Reference Nelson came into the season with 4.107 for service time which is 4 years + 107 days leaving him 65 days shy of a service year. Nelson began the season on the IL which still counts toward service time, and he was finally activated and optioned on May 24th which was the 58th day of the season, giving him 4.165 in service time, leaving him 7 days shy of 5 seasons. He was called up on again on June 5th, and remained up since, giving him 4 years + 172 days on Tuesday, June 11th, or 5 complete seasons.