If you blinked you might have missed it, but Minnesota Twins pitching prospect Logan Darnell made his major league debut in early May. It went well: three innings of scoreless relief against the Cleveland Indians on May 6th. He was sent back to the minors the next day, but Darnell is having a good year in Triple-A and should return to the majors at some point later this year.
Darnell was a sixth round pick in 2010 from the University of Kentucky. The southpaw hasn't ranked highly on prospect lists, but he's moved steadily through the system and has been very effective for Rochester this year, with a 2.54 ERA in 39 innings and a 41/14 K/BB ratio. This is one of the better runs of pitching in his pro career. He's had some struggles and took time to adapt to the high minors, but he has a four-pitch arsenal (88-92 fastball, curve, slider, changeup) and has made progress with his command.
This is generic lefty stuff on the surface, but if his command is sharp enough (and it has been this year) he can be a back-of-the-rotation starter or useful relief option.
Darnell is the type of cost-effective college pitcher that some teams will be looking for in the middle rounds of the 2014 MLB draft tomorrow.