Ervin Santana, while he does possess plenty of upside, has proven to be quite a volatile pitcher over his Angels career. His age (29) and his proven talent would make him an appealing trade target for a contender in need to rotation help.
WIth Garrett Richards displaying his ability to pitch at the major league level, Ervin Santana could become disposable. A rotation anchored by Jered Weaver, Dan Haren, and CJ Wilson can take a team very far, regardless of who pitches on days four and five. Jerome Williams and Garrett Richards would likely provide above-average production for those positions, anyways.
With all due respect to Alberto Callaspo, third base is a position where the Angels could afford to upgrade offensively. Though Youkilis is undoubtedly on the downside of his career, he brings offensive upside and World Series experience to a team that hopes to win the title this season.
Say what you will about his injury risk, it is a gamble the Halos can afford to take with capable replacements Callaspo and Izturiz on the bench.
Imagine rolling out this sort of lineup down the stretch:
CF - Mike Trout
RF - Torii Hunter
1B - Albert Pujols
DH - Kendrys Morales
LF - Mark Trumbo
3B - Kevin Youkilis
2B - Howie Kendrick
C - Chris Ianetta
SS - Erick Aybar
I think the addition of Youkilis far outweighs the loss of Santana. If it doesn't work out, Youkilis can leave as a free agent this winter.
But if it does work, the Angels would have a championship caliber offense that could truly rival the Texas Rangers, while still boasting one of the most fearsome rotations in baseball.