Here's an arm to watch for 2016: right-hander Ariel Jurado in the Texas Rangers system.
***He is still obscure on the national level. There's no publicly available video of him that I can post here, for example, nor any legally usable photos (though I'm working on that).
***This will change soon. People close to the Rangers have been buzzing about him for a couple of months now, and he performed well enough in the South Atlantic League this year to rank 11th on the newly-released Baseball America Top 20 Prospects list for that circuit (subscription required). You can expect to hear his name more as spring approaches.
***The sabermetrics: Jurado posted a 2.45 ERA this year in the Low-A Sally League, with a similar 2.62 FIP, going 12-1 (yes, W-L record means nothing for prospects but 12-1 is still cool enough to note) with a 95/12 K/BB in 99 innings. He allowed 92 hits, just five homers, and generated an unusual 3.13 GO/AO ratio.
***The scouting reports: Jurado is a 6-1, 180 pound right-hander signed out of Panama in 2012, currently age 19. As you would expect from the numbers his key pitch is a sinking fastball clocked between 89 and 95. Reports on his secondary pitches vary depending on time and source, descriptions of his curveball varying between below-average to fringe-average and of his change-up from fringy to plus. Everyone agrees he throws strikes with ease and shows excellent pitching instincts at his best.
***My guess is that the secondary pitches will become more consistent and not be an issue at higher levels. Ultimately his projection comes down to how well he can maintain his peak velocities and how durable he is. If the heat stabilizes in the low-90s and I'm right about the secondaries, he could max out as a number three starter. If durability becomes an issue or he winds up with two pitches instead of three, he could be a solid middle reliever.
Either way, he's definitely worth tracking. My early thinking on a grade is C+/B-.