C - Carlos Ruiz - Product of the Phillies farm system
1B - Ryan Howard - Product of the Phillies farm system
2B - Chase Utley - Product of the Phillies farm system
SS - Jimmy Rollins - Product of the Phillies farm system
3B - Pedro Feliz - Free agent signing
LF - Ben Francisco - Acquired in trade with the Indians. The players given up were all players in the Phillies farm system
CF - Shane Victorino - Rule 5 draft pick
RF - Jayson Werth - Free agent signing
DH - Raul Ibanez - Free agent signing
SP - Cliff Lee - Acquired in the same trade with Ben Francisco, so like Francisco, an indirect product of the Phillies farm system.
C - Jorge Posada - Product of the Yankees farm system
1B - Mark Teixeira - Free agent signing
2B - Robinson Cano - Product of the Yankees farm system
SS - Derek Jeter - Product of the Yankees farm system
3B - Alex Rodriguez - Hard to classify. He was re-signed this offseason, so he could be considered a free agent signing. He was originally acquired in a trade where the centerpiece was Alfonso Soriano. However, while Soriano was a product of the Yankees farm system, there was a serious bidding war for him when he "retired" from Japan to come to America.
LF - Johnny Damon - Free agent signing
CF - Melky Cabrera - Product of the Yankees farm system
RF - Nick Swisher - Acquired in a trade with White Sox for Wilson Betemit. Betemit was acquired from the Dodgers for Scott Proctor, a product of the Yankees farm system.
DH - Hideki Matsui - Free agent signing
SP - CC Sabathia - Free agent signing
10 or 11 (depending on how you classify A-Rod) out of the 20 starters in game 1 of the World Series can be tracked to each respective team's farm system, either directly or indirectly. Phil Hughes just came into the game too, a direct product of the Yankees farm system.
Neither of the Phillies nor the Yankees would be here without the free agents they signed. It's not as if free agent signings are not important. However, a team's backbone is its farm system, even when it has a $200 million payroll. Seriously, name a good prospect that came out of the Yankees farm system between the Yankees last World championship and today. Don't get me wrong, Mark Teixeira and CC Sabathia were massive additions to the Yankees this season - but Robinson Cano, Melky Cabrera, Joba Chamberlain, and Phil Hughes have developed over the past couple seasons too.
Teams live and die by their farm systems. The only way to create a consistent winner is through a strong farm system.