This is part of a series highlighting several prospects in our 2019 Top 100 Prospects midseason update. To see the full rankings, click here.





Rank: 83

Preseason: 27

STOCK is headed: Down 📉

The Mariners acquired Sheffield as the top prospect from the Yankees in the deal that sent James Paxton to New York last winter.

So far, Sheffield’s introduction to the Mariners’ system has been rough.

The 23-year-old lefthander went 2-6, 6.87 in his first 13 appearances (12 starts) with Triple-A Tacoma before being demoted to Double-A. Most concerning was his 41 walks and 48 strikeouts in 55 innings. He also walked four batters in two innings in his first outing with Seattle.

Sheffield has stabilized a bit in Double-A, posting a 1.36 ERA through five starts. He has 34 strikeouts compared to just seven walks in 33 innings.

Sheffield boasts a mid-90s fastball and promising slider from the left side, but his high-effort delivery has long made evaluators skeptical he would throw enough strikes to be a major league starter.

His showing so far this season hasn’t done much to change that assessment.

“He doesn’t do it easy,” one longtime scout said. “The biggest thing is: Can he get himself under control in his delivery? I think he’s probably on course to be a reliever. He never really developed the finesse needed to be a true starter. His scatter is pretty large even in short stints.”

Sheffield has shown better and has time to recover, but the believers that he can remain a starter are dwindling.