I'm a little late on this, but Baseball America is in the process of releasing its 2014 "Top 20 Prospects" rankings for each Minor League. They posted the top 20 for the Gulf Coast League last week and the NY Penn League earlier this week. Yankee farmhands nabbed 2 spots on the GCL list, shortstops Jorge Mateo and Angel Aguilar at #4 and #15 respectively, and catcher Luis Torrens came in at #4 on the Penn League list. Mateo is a 19-year-old shortstop who hit .276/.354/.397 with 14 R scored and 11 stolen bases in 15 games for the GCL Yanks 1 team (65 PA). Aguilar, also 19, hit .311/.373/.536 with 7 HR, 34 R, and 31 RBI in 39 games for the GCL 2 team (167 PA). Torrens hit .270/.327/.405 in 202 PA for the Staten Island Yanks after an early appearance in Low-A Charleston and a shoulder injury. He's still only 18 years old and arguably the Yankees' best low-level prospect.
You can find the complete lists for all the leagues that have already been released and more detailed scouting reports from BA right here. The reports are for subscribers only.