Here's another "now you see him, now you don't" prospect: Baltimore Orioles lefty Ariel Miranda, promoted to the major leagues on July 3rd then sent back to the minors on July 4th after giving up four hits and two runs in two innings of relief. He also fanned four and has performed well enough in Triple-A to merit more opportunities.
Basic background from the 2016 Baseball Prospect Book:
Ariel Miranda, LHP, Baltimore Orioles
Bats: L Throws: L HT: 6-2 WT: 190 DOB: January 10, 1989
The Orioles signed Miranda as a Cuban free agent last spring. He did not have much hype but he did have a pretty good track record in Serie Nacional over parts of seven seasons, posting a 3.78 ERA in 386 innings with 274/151 K/BB. His fastball is in the 89-93 range but he mixes it well with a solid-average change-up and a deceptive splitter as his out pitch. He also has an easy delivery, although he did miss time late in the year with a sore shoulder. Miranda is too old to project huge improvement but he adapted to the United States rather quickly and has potential as a back-end starter or bullpen option. Grade C.
Miranda has thrown 148 innings in the United States, half that at the Triple-A level, posting a 3.84 ERA with a 143/50 K/BB and 129 hits allowed, not far off from what he did in Cuba. He generates decent velocity with relatively little effort, topping out at 95 in shorter stints and usually in the 89-93 range. His best pitch is widely-regarded to be the splitter. The straight change draws mixed reviews, some sources rating it solid-average while other see more of a fringy pitch. His main breaking pitch is a slider and is a clear step behind the fastball and splitter in terms of quality. He's shown a reverse platoon split since reaching the high minors, which dovetails well with questions about his breaking ball and makes him less than ideal for use as a LOOGY.
That said, Miranda has positive traits to work with: decent velocity, at least one solid secondary pitch, solid control, and an easy delivery. He could end up being a useful back-end starter or a bullpen option if his strengths and weaknesses are properly understood.