If you blinked you may have missed this: on May 15th the Blue Jays promoted rookie right-hander Dustin Antolin to the major leagues. On May 16th he pitched two innings of relief against the Tampa Bay Rays, giving up four hits, a walk, and three runs in two innings while fanning one. This morning, May 17th, he was sent back to Triple-A Buffalo.
OK, so who is this one?
Antolin was originally drafted by the Blue Jays in the 11th round back in 2008 from high school in Mililani, Hawaii. Used almost exclusively as a relief pitcher, he moved through the system quite slowly, losing time to Tommy John surgery in 2011 and working through command problems. He was effective in the high minors beginning in 2014, posting a 3.07 ERA with a 55/18 K/BB in 56 innings in Double-A last year, but by the end of 2015 he was considering retirement.
He decided to stick with it one more year, moved up to Triple-A Buffalo for 2016 and gained attention with a 2.70 ERA and a 25/11 K/BB in 20 innings, seeing some use as a closer with three saves in four chances. And now he's in the baseball encyclopedia.
Antolin is a 6-2, 230 pounder, age 26. He has standard bullpen stuff with a four-seam fastball in the 90-94 range, a frequently-used change-up in the 80s, and a few sliders in the 80s. His command took a major step forward back in 2014 and moved him from roster-filler to fringe prospect. He would clearly need some adjustment time to make it work in the majors but there's enough stuff here if the command holds up for him to be a workable bullpen asset.
Here's some Fangraphs video that gives the general idea.