The worst thing you can do is bring in a proven ace.
I know that sounds stupid, but it is true
Would you not rather have a ace prove himself on your team?
You are much better off in terms of young talent and cash if you discover your own ace.
08 - Hamels
07 - Lester (little bit of a stretch)
06 - Carpenter
05 - Buehrle
04 - Pedro (little bit of a stretch)
03 - Beckett
02 - Lackey
*all led their teams to world series wins
In case nobody has noticed, the best way to win is to find, not buy an ace.
One of: Hughes, Kennedy, or Chamberlain will lead the Yankees to a World Series soon.
If it is not them, then it will be another young gun, because the Yankees will have tons of draft picks if they can refrain from the proven aces.
Their is a saying that you hear in school. Advice for a good leader, who wants to prosper and rule for a long time - "use history as an example"
Whichever team can realize this proper formula for winning wins the world series year in and year out.