There is an excellent, excellent piece at Grantland by Rany Jazaleri that covers why the most successful franchise in the history of Major League Baseball will be distinctly mediocre in the future.
Rany goes into deep detail about why this is. How the Yankees over-performed last season. How paying hundreds of millions of dollars for Brian McCann and Jacoby Ellsbury almost makes up for losing Robinson Cano. How this Yankee team is amazingly, amazingly old. In fact, they were the only team in MLB last season with a roster than had an average age of 31 or higher. Signing a 30-year-old Ellsbury actually makes the Yankees younger.
Members of the Yankees' 2014 lineup
But the biggest reasons lie in two areas. First, the well-known Yankee penchant for signing or trading for big-name players. When they sign them as free agents, they lose draft picks. When they trade for them, the Yankees give up whomever happens to be the best players in their farm system at that time. The result is a barren farm system that cannot supplement an aging team with any comparable level of talent. As Rany points out:
There also isn't enough talent on the way. You'll notice that, in this entire article, I've yet to mention a single prospect or rookie who's ready to step in for the Yankees, giving them upside and youth in a nice, payroll-cleansing package. That's because they don't have any. While the Red Sox have Bogaerts and Bradley ready, the Rays have a full season of Wil Myers in store, the Blue Jays have Aaron Sanchez and Marcus Stroman, and the Orioles have the electric Manny Machado along with pitchers Kevin Gausman and Dylan Bundy, the Yankees have … bubkes. No rookies, no second-year players who might take a step forward. Their farm system is terribly weak; Jason Parks, the chief prospect guru for Baseball Prospectus, recently described it as "[Double-A catcher] Gary Sanchez and a list of interchangeable prospects with reliever profiles or bench futures." By comparison, the Red Sox's farm system is so deep that, according to Baseball America's Ben Badler, they may have as many as 10 of the top 100 prospects in baseball.
And he isn't wrong about the Boston system. Living outside of Portland, ME I get to see these guys. And there is some major talent that will be hitting Boston in the next couple of years.
And that leads the the second reason why the Yankees are going to slide and slide hard. And it's almost easy to miss. Rany mentions it towards the end of his piece but it is important and I think is the over-arching reason why this is happening. Again, from Rany:
