One of the most obvious reasons for their downfall is the rising age of the team.
Mark Smith over at It's About the Money brilliantly laid out the information for the Yankees and their age.
Last season, the Yankees had a team average age of 30.6 years old, with the lineup coming in at 31.7 years and the starting rotation coming in at 29.6 years. The Major League average age for a team was right around 27 years old. Needless to say, the Yankees are obviously above the league's average age.
The lineup is not going to get any younger anytime soon. With players such as Alex Rodriguez, Mark Teixeira and Derek Jeter still under contract for a few more years, the average will only increase. Not to mention, Robinson Cano, Brett Gardner and Curtis Granderson are all approaching 30 years of age.
The only glaring locations in the Yankees lineup that might get younger in the near future appear to be catcher (with Austin Romine potentially arriving in 2013) and right field.
The starting rotation is an area of strength in the youth department for the Yankees. The eldest member of the staff is AJ Burnett at 35 years old, and he may not even be in the rotation this season. He will be battling for a spot with 25-year-old Phil Hughes and fellow 35-year-old Freddy Garcia.
Recently signed Hiroki Kuroda takes the crown as the oldest officially in the rotation at 36, with CC Sabathia coming in second at 31. Once you throw in newly-acquired Michael Pineda (who is only 23), and 24-year-old Ivan Nova, the Yankees have a chance to grow with a younger rotation. After this season, look also for Dellin Betances and Manny Banuelos to potentially fight for a spot in the rotation.
The point is, with the Yankees continually growing in age, their bodies are bound to break down (a la Alex Rodriguez the last few years) and see a decrease in production.