I brought this up before, here, and endured a colossal statistical foray about why this was not going to happen.
Well, guess what, CC can't stop the righties, starter Warren is needed in the bull pen. Cueto's gone to the Royals, Hamels is still there but will probably be more expensive.
If the Yanks' lead starts melt in the Texas heat, next week, Cashman may have no choice.
http://www.nj.com/yankees/index.ssf/2015/07/whos_pitching_for_the_yankees_next_tuesday_tbd_but.html
http://hardballtalk.nbcsports.com/2015/07/25/yankees-may-call-up-luis-severino-next-week/ 
It's one thing to make the kind of trades we used to make with Kansas City in the '50s and '60s, giving away older players and "never will be" prospects for guys like Maris. But you don't give up the best pitching prospect in your minors, a 20 year old kid who has done it at every level so far, for a rental.
CC is a shadow of his former self
Pineda (who we need as THE #1), shows signs of wilting
Tanaka (the goose who laid the golden egg), needs kit-glove care
Nova, coming back from Tommy John, ditto
Eovaldi, (10 wins) looks the most promising
The FUTURE is NOW, tomorrow is not guaranteed; other contending teams are posturing to get better for the late run (not going to happen with just more vet "bodies").
Cashman doesn't want to give up the top prospects, that's fine, then USE THEM !
+1
The Yanks have a very high value on Judge as a future cornerstone cleanup hitter and RF. Cashman is correct to keep him too.
Bird and Sanchez are blocked by Tex and McCann so it is a lot easier to trade them. It is also easier to let go of a 1st base prospect because there are more of those. Sanchez might be the more valuable piece to another team because he is a catcher and quality starting C's are hard to find. Bird is also a pretty weak fielder so the Yanks might not want a young DH clogging up that spot. They like to give the DH to an older player
It's not like he's 15 (Joe Nuxhall), or 17 (Bob Feller)