My apologies if this is old news, but I couldn't find any mention of it anywhere in the Pittsburgh sports media. Baseball America published a list of recent Cuban signees today, and down toward the bottom of the list, they include the signing to which I alluded in the headline. BA lists Lopez's age as 20, describes him as a "sinker/slider pitcher who can run his fastball up to the low 90s," and notes that his signing has not yet been made official due to visa issues. Those visa issues could suggest that his listed age may not be his true one, as there's a significant history of age fraud with Cuban defectors, and verification is obviously difficult due to the state of relations between Cuba and the US.
I haven't been able to locate much additional information on Lopez. This article at Terreno de Pelota indicates that Lopez had been a member of the Industriales, a Havana-based team in the top-level Serie Nacional. The article also describes Lopez's performance at a workout last April, where his fastball sat at 90-92 MPH and touched 93, along with "an excellent change and slider." If that report is accurate, it makes him sound like a very intriguing talent.
It's interesting that a signing this significant would have remained below the radar for so long. The situation is certainly worthy of continued attention, and I will post any updated information that I am able to discover.