The Cubs were known to be in the market for a left-handed reliever, and today they made a deal to acquire Mike Montgomery and a "Triple-A Starter" from the Seattle Mariners for DH Dan Vogelbach and pitcher Paul Blackburn. There are reports that there may be more to this trade than just that, but that is the deal as we know it now.
Montgomery, 26, was a former top prospect in the Royals and the Rays organization, where Joe Maddon became familiar with his work. He was traded to the Rays as part of the James Shields deal and he went to Seattle in exchange for Erasmo Ramirez in 2015. He was a starter in 2015 to mixed results, but has pitched mostly out of the bullpen this season. He's been terrific in the pen, posting a 2.34 ERA in 61.2 innings. He's struck out 54 batters and has shown good control with only 18 walks. He's been especially deadly on left-handed hitters, holding them to a .164 batting average and a .269 OBP.
Montgomery is under team control until 2022 and is not arbitration-eligible (assuming the rules on that don't change in the next CBA) until 2019. His youth and years of team control were undoubtedly a big factor in the Cubs interest in Montgomery.
Going to Seattle is 1B/DH/Folk Hero Dan Vogelbach. Vogelbach is leading the PCL in on-base percentage and is second in OPS. He is a superior hitter who can hit to power to all fields. He is, unfortunately, a poor fielder who is pretty much destined to be a DH, which makes him a better fit in Seattle. Baseball America ranked him as the 25th-best Cubs prospect coming into the season, but I and others have ranked him much higher. Even BA noted that his stock was rising in a recent update.
Paul Blackburn was the Cubs first-round supplemental pick in 2012 and has slowly moved up the system each year. He was ranked as the Cubs 19th ranked prospect by Baseball America in the most recent rankings. Blackburn has a 93-94 mph fastball and a decent curve, that, when working, attacks the bottom of the zone. In 18 starts in Tennessee this season, Blackburn was 6-4 with a 3.17 ERA over 102.1 innings. He's struck out 72 and walked 26 while holding opposing hitters to a .244 average.
This post will be updated if and when more information becomes available.
Update: And here's your Triple-A pitcher.