After stealing Alberto Del Rio from AAA they seem to be targeting another top star but this time from the other top Mexican promotion known as CMLL. This company has been in business since 1923 and was the WWE of Mexico and seen competition between themselves and AAA.
Sombra had been given a tryout by the WWE back in 2011 and though we haven't really heard anything about it since then. La Sombra has also worked in Japan previously specifically working for New Pro-Japan Wrestling. I think the expansion for the WWE to give International stars a chance to make an impact in NXT and on a National scale is a great chance that didn't exist a long time ago.