Nelson (shoulder) will miss a "meaningful" portion of the 2018 season, according to general manager David Stearns, Adam McCalvy of MLB.com reports.
There is not a concrete timetable for Nelson's return from mid-September surgery to repair his labrum. He carries a lot of risk in single-season leagues, as it's possible he could miss several months. However, he proved this year that he has top-of-the-rotation upside when he's healthy, posting a 3.49 ERA, 1.25 WHIP and 199 strikeouts in 175.1 innings.