OF, Jake Cave - Arguably nobody's stock has increased more since the start of the 2016 season than this former 2011 sixth round pick. He began the year as part of the Cincinnati Reds organization after his Rule 5 Draft selection back in December and has since torn the proverbial cover off of the ball since his return to the Yankees, hitting a combined .310 in his first 40 games.
However, few questioned his ability to hit, run the bases, or even play defense; it was his power that was always the back-burning question mark and he's begun answering the bell in a big way so far in 2016. He's slugging over 200 points higher so far in 2016 than he was a year ago and he's already just two home runs away from his career-high and the calendar hasn't even flipped to June yet.
With Mason Williams still rehabbing his way back and Slade Heathcott unable to play everyday due to his checkered injuries, the door is beginning to widen considerably for what many once considered an outfield prospect simply buried on the Yankee depth chart not all that long ago. His stock is soaring and he very well may get his big league chances in Yankee Stadium sooner rather than later.
LHP, Nestor Cortes - It was quite surprising when this former 36th round pick back in 2013 didn't break Spring Training camp with the low-A Charleston RiverDogs this year, especially considering the rather dominating performance he strung together in short-season Pulaski last season [6-3, 2.26 ERA, 66 K's and just ten walks]. Perhaps too good for Extended Spring Training, he dominated there once again this year after doing so there last year.
Though his promotion to the South Atlantic League was not immediate this year, his impact has been. He's allowed just twelve base runners in his first four outings, struck out 27 batters in 19.2 innings, and his strikeout to walk ratio is even better than his career 6.29 mark. Forget how hard he throws or doesn't throw, the Yankees need to keep moving him along until he proves there's a level that can hit him even remotely on a consistent level because so far there hasn't been one.
A non-Top 50 prospect entering the season, he's a bonafide one these days with the Manny Banuelos-like numbers he's putting up so far in A-ball.
SS/2B, Thairo Estrada - Just like Cave few questioned this Venezuelan native's ability to be a consistent hitter, a good base runner, and a very good defensive player. Everyone knew he had all of those traits in spades despite his extreme youth and he went out and proved it immediately this season, hitting .286 with eleven stolen bases in just 35 games for low-A Charleston in his first taste of the long-season leagues before earning a quick promotion to high-A Tampa.
However, just like Cave, while many team insiders believed there was power in his swing it had not yet translated into on the field production and that is quickly beginning to change. The 20-year old middle infielder has already more than doubled his career home run total [he had just four entering the season and has now clubbed six already in 2016] and we're barely one-third into the season, and he's done it playing his home games in pronounced pitcher's parks too.
What is even scarier though is that a player with essentially no weaknesses in his game is only getting stronger in every area of his game and that has his stock soaring to all new levels.
2B, Billy Fleming - The emergence of Estrada and this former undrafted minor league free agent at the second base position is great news for the long-term prognosis for the Yankees and perhaps bad news for others vying for playing time at the same spot. Fleming, a noted batsman during his collegiate days at the University of West Virginia where he hit .351 in his final season, has flashed the same kind of bat control at the professional level too as his .325 average thus far in 2016 is right in line with his career .332 mark.
However, few questioned his ability to hit for average. It was his less than average power potential and rather questionable defense that never really allowed him to become much more than an organizational afterthought among prospect analysts entering the season. The defensive game though is beginning to creep up to the average vicinity and his power is starting to come now that he is getting everyday reps; he's among the doubles leaders in the farm system and he's already set a career-high in home runs  just one-third into the season.
If he can keep collecting extra-base hits with the way above batting potential and consistency he's shown thus far all while playing solid defense then the Yankees could have a real find on their hands. As it stands right now he's gone from pretty much an 'NP' [non-prospect] to an intriguing prospect with his play so far in 2016.
RHP, Giovanny Gallegos - This Mexican native has long been undervalued and underappreciated in prospect circles. Perhaps it's because he doesn't throw 97 mph consistently or because injuries slowed down his development at the lower minor league levels. Whatever the reason though, this 6-foot-2 right-hander is back on the prospect map in a big way with the way he's performing so far in 2016.
All he's done so far this year is post a combined 1.42 ERA between Double-A and Triple-A, post a sub-1.00 WHIP ratio [0.95 to be exact], and strike out nearly 14 batters per nine innings! Buried on the reliever depth chart entering the season, injuries to the likes of Jacob Lindgren and Nick Rumbelow have allowed Gallegos to find his way further up the depth chart.
Pulling a Cesar Vargas-like reclamation to his prospect status, Vargas' success at the big league level should also serve as a cautionary tale for the Yankees and their fans that giving up on a once promising pitching prospect too prematurely may be unwise and Gallegos is pitching his way back into Top 50 consideration.
LHP, Jordan Mongtomery - This former University of South Carolina standout falls more into the Cave-Estrada camp as more of a solid bonafide prospect entering the season whose game and resulting stock are beginning to jump to a completely different level in 2016. Sure Montgomery's fastball is beginning to sustain more power than it had in previous years, sitting more comfortably in the 91-94 mph range and his breaking ball continues to keep getting better, but it's his consistent on the mound production that simply can't be ignored at this point.
He's quickly become one of the safer bets pitching-wise to give his team six solid innings of just a couple runs allowed, less hits than innings pitched, and nearly as many strikeouts. It's quite bankable and that alone is worth its weight in gold these days -- the innate consistency -- and that has his stock rocketing to new heights these days, especially as he mows down Double-A batters. An innings eater with the production to back it up is in high demand these days and arguably nobody's stock has increased more since the start of the 2016 season, and he's not all far off from helping out the big league club.
OF, Kendall Coleman - You can't write off a prospect after just 366 career at-bats but it's at least a decent barometer on how the progress is going and in Coleman's case his .205 average in 2016 so far is pretty much right in line with his career .213 mark and that's not good news. He still has enormous upside and he's health for the first time in four years but the production has to follow soon to help reverse his slipping stock.
RHP, Simon De La Rosa - Arm-wise and stuff-wise this Dominican native as is legit as it gets, sitting comfortably in the 93-95 mph range with a really good breaking ball. There was [and perhaps still is] a prevailing thought that he might be better served coming out of the bullpen as a grip it and rip it reliever but his [at best] lackluster command clouds that possibility too. He needs to improve on his 1.5 strikeout to walk ratio in a hurry to save his eroding stock but at 23 years old and still in A-ball that doesn't seem all too likely at this point.
RHP, Ty Hensley - Nobody ever wants to officially proclaim a prospect's particular stock dead but few have ever had or ever will have a larger potential comeback from proverbial life support than this former first round pick. He entered the season tallying just 42.2 innings over his first four professional seasons and he not only won't be adding to that total in 2016 but he might be hard-pressed to add much to that total in 2017 either after it was learned he needs a second Tommy John surgery. The stock might not be officially dead but it pretty much has no value at this point.
2B, Gosuke Katoh - A poster-boy for how quickly one's stock can change in either direction, this former second round pick was once considered a real up-and-comer in the Yankee farm system. However, two and half years later and still just 21 years old, Katoh's stock is at an all-time low. Part of that isn't even his fautl as the emergence of Estrada and Fleming at second base have further buried Katoh on the depth chart, and now the likes of Hoy Jun Park, Kyle Holder, and even Jorge Mateo have added second base to their defensive repertoires even before Katoh made his way back into the long-season leagues. All of that is not good news for a player who hasn't come close to hitting well in the long-season leagues yet and doesn't offer much in the way of defensive versatility.