4. RHP Chandler Shepherd
Though MLB.com has him ranked No. 22 on their Red Sox prospect ranking heading into 2019, Shepherd is starting to straddle the line of being too old to be called a prospect (26, 27 in August). But he has pitched a lot in Triple-A (77 appearances), with a boost in strikeouts over the last two seasons at that level (8.3 K/9) while maintaining good control (2.5 BB/9).
Shepherd has four average-to-above average pitches, so his move to being a starter in Triple-A last year (25 starts) was not too surprising. The path to pitching in Boston is best paved to the bullpen right now though, and Shepherd has been a reliever for most of his minor league career.
The ceiling here doesn’t look great, and a drop from a 10.3 K/9 mostly as a reliever for Pawtucket in 2017 to 7.4 K/9 as a starter last year stands out as a potential concern for any semblance of viability as a major league starter. But Shepherd could easily make his major league debut this year as a bullpen arm, and pitch well enough to stick around awhile.