The Core Four: Who's No. 1?

They have become known as the “Core Four" - Derek Jeter, Mariano Rivera, Andy Pettitte, and Jorge Posada.

They're the only members of the 2010 Yankees who were around when this playoff run started in 1996. More importantly, these four men all came up through the Yankees system and have each played vital roles in the franchise's championship runs.

They symbolize the winning ways of the franchise and the fans hold on to these four men more than any other players on the team. Following this postseason, this may be the last time these four men ever play together again. Jeter, Rivera, and Pettitte are all free agents at the end of 2010.

So, here's the question: Who is most indispensable of the four? Below, we make the case for each. Read, decide, then vote.

Derek Jeter

Named the Yankee captain in June 2003, Derek Jeter has been one of the most revered players in all of sports. Jeter has been a model of consistency in the regular season averaging 208 hits per season. The 16-year veteran is an 11-time All-Star who flourishes in the postseason. The 1996 Rookie of the Year has the record for postseason hits (175), at-bats (559), and runs scored (99).

In 2009, Jeter passed Lou Gehrig to become the Yankees’ all-time hit leader. In 2000, Jeter was the first player ever named All-Star and World Series MVP in the same season. He's the only player in MLB history to do so. Jeter has won three Gold Gloves, but more importantly his defensive gems in postseason baseball stand out among the best. Just ask Jeremy Giambi.

With contract negations coming up in a few months, Jeter had the  worst season of his career in 2010. His .270 batting average was the worst in any of his 15 full seasons (he had never batted lower than .292). His on-base percentage and slugging percentage also hit career lows. Yet, he stands 74 hits away from 3,000.

Andy Pettitte

Andy Pettitte has been a big-game pitcher for the Yankees ever since his debut in 1995. In his second season he won 21 games and led the Yankees to their first World Series victory in 18 years. Pettitte would again win 21 games in 2003 before leaving the Yankees to pitch for his hometown team, the Houston Astros, for three years. Upon his return to the Yankees in 2007, he has increased his franchise win total to 209 wins. Pettitte has the most postseason starts (40) and wins (18), which includes six series clinching wins (he pitched in each of the clinching games in the 2009 playoffs). All are MLB records.

Pettitte was injured for most of 2010, but the Yankees were able to secure a playoff spot. He still managed 11 wins in only 21 starts with an ERA of 3.28. Pettitte will make up for lost time with his bread and butter- the postseason.

Jorge Posada

Jorge Posada is a five-time All-Star who has been of the best catchers in all of baseball. Posada is the only catcher to hit .330, with 20 homers, 90 RBIs, and 40 doubles in a single season. Since 2000, Posada has more homers and RBIs than any other catcher. He is the last Yankee catcher to have hit 30 homers since Yogi Berra. His accomplishments extend to his ability to handle a pitching staff and call a game. He also holds the record for the most games caught in postseason, with 101. Posada has made six straight opening day starts, second to Thurman Munson who made 10 straight from 1970-1979.

Posada continues to put up solid offensive numbers and catch regularly despite the physical demands of his position. His average slipped to .248 as he battled foot, knee, calf, head and finger injuries in 2010, but he still put up respectable power numbers, smacking 18 home runs and driving in 57, with a .454 slugging percentage.

Mariano Rivera

There is not much left to be said about a guy who has dominated his peers for 16 years with one pitch. Closers are known for having a short career, but Mariano Rivera has made a living closing out big games for the Yankees year after year, thanks to his dominating cutter.

Rivera has 559 career saves, second all-time to Trevor Hoffman. As great as the 11-time All-Star has been in the regular season he’s been even tougher in the postseason. Rivera holds the record for the most saves (39), appearances (88), and lowest ERA in postseason (0.77). Many teammates, past and present, agree that if not for Rivera, the Yankees would not have been as successful in the past 16 years.

The only thing that’s sure this postseason is if the Yankees have a lead after eight innings, Mo will be on the mound. No matter how bad the Yanks looked going down the stretch, they always have Rivera. That’s an edge no team can match.