Sheffield was traded to the Mariners along with Dom Thompson-Williams and Erik Swanson in exchange for James Paxton, Ryan Divish of The Seattle Times reports. Like Paxton, Sheffield is left-handed and sits in the mid-90s with his fastball. His prospect stock has slipped since early in the 2018 season, as his stuff has backed up slightly. This move improves Sheffield's stock in dynasty leagues, since he should now have no problem joining a big-league rotation fairly early in the 2019 season, whereas the Yankees may have kept him at Triple-A for further development or deployed him out of the bullpen. In addition to Sheffield's plus fastball, he has a plus slider and will flash an average or better changeup. His stuff plays down slightly due to his fringe command, but he can dominate when he is throwing strikes. The Mariners are in a full rebuild, so they may play service-time games with Sheffield early in the season, but he should be up in the big leagues at some point in the first half if he is performing well.
The Yankees officially selected Sheffield's contract from Triple-A Scranton/Wilkes-Barre on Tuesday. Sheffield joined the Yankees over the weekend after Scranton/Wilkes-Barre's season came to an end, but he wasn't officially added to the 40-man and active roster until Tuesday, when New York finally made a transaction to clear a spot for the 22-year-old. The lefty is expected to provide the Yankees with a power arm out of the bullpen over the final two weeks of the regular season. If he thrives in his first exposure to big-league hitters, Sheffield could secure a spot on the Yankees' postseason roster.
Sheffield's contract was selected by the Yankees on Saturday, Conor Foley of The Scranton Times-Tribune reports. Sheffield shifted to the bullpen at Triple-A Scranton/Wilkes-Barre in preparation to join the Yankees, and will now do so with a couple weeks remaining in the regular season. The 22-year-old allowed two runs over 13.1 innings as a reliever with the RailRiders and posted a 2.77 ERA and 1.21 WHIP before that as a starter.
Sheffield may not join the Yankees as a September callup, Pete Caldera of The Bergen Record reports. The Yankees' 40-man roster got more complex over the last couple days with acquisitions of Andrew McCutchen and Adeiny Hechavarria, complicating Sheffield's potential promotion. The 22-year-old shifted to the bullpen at Triple-A Scranton/Wilkes-Barre in mid-August in preparation to join the Yankees, but general manager Brian Cashman is now indicating that a move is not guaranteed. The young left-hander has a 2.53 ERA and 1.16 WHIP over 113.2 innings between Double-A and Triple-A this season.
Sheffield was moved to the bullpen Friday in preparation for his September callup by the Yankees, Jack Curry of YES Network reports. General manager Brian Cashman had previously said Sheffield would pitch for the Yankees in 2018, but had not specified whether that would be as a starter or a reliever. The 22-year-old will make a few appearances out of the bullpen with Triple-A Scranton/Wilkes-Barre before joining the Yanks next month.