The Yankees selected Jacob Lindgren as their first pick in the 2014 Draft. The lefty hails from Mississippi and was drafted out of Mississippi State where he spent the better part of his time as a starter before being converted to a reliever during his 2014 season. Lindgren accredited the switch with an increase in velocity and said that it allowed his slider to play better. Scouts consider both to be plus pitches, with the fastball sitting in the low to mid-90s and his slider described as "a true wipeout pitch with late bite at 82-84 MPH."
Lindgren had quite a year, starting with the 55.1 innings that he threw in relief for Mississippi State while sporting a 0.81 ERA and notching 100 strikeouts. After being drafted by the Yankees, he flew through the lower levels of the minor leagues rather quickly while earning the nickname "The Strikeout Factory." He pitched one whole inning in the Gulf Coast League before being promoted to Charleston where he recorded 11 strikeouts and 0 walks through 5 innings pitched. He increased his K/9 up to 20.9 in Tampa, with 17 strikeouts and four walks in 7.1 IP. Lindgren finally ended the season in Trenton, where he fell back to Earth a bit. This was primarily due to one really terrible outing, his last of the season, where he walked three batters and was charged with four earned runs while only recording one out. Lindgren pitched 11.1 innings in Trenton with a 3.97 ERA, 1.32 WHIP and still really impressive K/9 of 14.3. He ended his first partial year in the minors with 48 total strikeouts through 24.2 IP giving him 17.5 K/9 overall.
Since he has been invited to spring training, it's absolutely possible that Lindgren could be pitching out of the Yankees' bullpen come April. However, since they didn't call him up in September, and he finished the season in Double-A, it could be that they want him to get more experience in the minor leagues. It could also be that Yankees just didn't want to fatigue Lindgren since he started the year pitching college ball, and that they otherwise would have let him play in September.
In a recent interview, Lindgren said that he noticed that batters were taking more pitches when he Double-A. His walk rate did start to rise as he worked through the farm system, so it'll be interesting to keep an eye on that in 2015, as well as his strikeout rate, obviously. Regardless of whether he starts the season in Trenton or Scranton, if Lindgren can keep up last year's level of play then at the very least he should be called up when the roster expands.