PHILADELPHIA -- The Phillies understood the unique opportunity that presented itself the moment Cliff Lee returned to Philadelphia in December.

They had assembled a rotation for the ages, and they needed to take advantage of it. Sure, they would have Roy Halladay, Cliff Lee and Cole Hamels under contract through 2012, but there are no guarantees in baseball. Just because the talent is there, it doesn't mean the production will be there.

It doesn't mean everybody will be healthy.

It doesn't mean they will win.

The Phillies entered the 2011 season hungry and played like it. They captured their fifth consecutive National League East championship and are on their way to finishing the regular season with the best record in baseball.

But the Phillies know that means nothing once September turns to October. Their loss to the San Francisco Giants in the 2010 National League Championship Series is a good reminder the team with the best regular-season record isn't guaranteed a trip to the World Series.

They have to earn it.

Here are the 10 reasons the Phillies are back in the postseason:

The Rotation: Halladay, Lee and Hamels have been three of the top pitchers in the National League this season. Nobody can question that based on their rankings in numerous statistical categories. In fact, entering September, it seemed there was a three-horse race for the National League Cy Young Award among Halladay, Lee and Dodgers left-hander Clayton Kershaw. Hamels could have been in the Cy Young mix, but he missed a couple of starts in August because of inflammation in his left shoulder.

Roy Oswalt missed much of the season because of a back problem, but the Phillies are hopeful he is strong entering the postseason. However, Oswalt's absence allowed Vance Worley to earn a spot in the rotation, and he should earn some NL Rookie of the Year Award consideration after his performance.

A Solid 1-2 Punch in the 'Pen: Before the season started, the Phillies had Brad Lidge and Ryan Madson as their closer and setup man, respectively. It turned into Jose Contreras and Madson because of a right shoulder injury to Lidge before it became Madson and Antonio Bastardo because of an elbow injury to Contreras.

Madson and Bastardo have been nearly unhittable for most of the season. It's safe to say the Phillies' record would have been much different if Madson had not acclimated himself so nicely as the closer and Bastardo had not established himself as one of the toughest left-handed relievers in the game.

Shane Victorino: When people think about the Phillies' offense, they naturally think of Ryan Howard, Chase Utley and Jimmy Rollins, but Shane Victorino has been the lineup's true heart and soul in 2011. He has been among the NL leaders in batting average, on-base percentage and slugging percentage for much of the season. And it hasn't mattered much where he has hit. Because of his pop and speed, he has hit first, second, fifth and sixth. His versatility has been great for manager Charlie Manuel, who can slot him anywhere.

Hunter Pence: The spring following the Phillies' 2008 World Series championship, former general manager Pat Gillick spoke of the importance of bringing in fresh blood onto a winner so players don't become complacent. Not that the Phillies were complacent, but Pence provided a jolt of energy to the clubhouse and lineup upon his arrival on July 30. He also provided Manuel with a solid right-handed power bat to hit behind Howard, giving him some much needed balance in the lineup.

Chase Utley: Remember in Spring Training when there were legitimate concerns over Utley's ability to play this season? Utley returned to the lineup on May 23, providing stability to second base and the lineup. Yes, Utley has not been as productive offensively as he has in the past, but he has shown flashes. But the key here is the Phillies did not need to find a long-term replacement at second base, which allowed them to trade for Pence.

The 2008 Draft: Before the season started, most people in the Phillies' front office seemed to think Worley and Michael Stutes would contribute to the team at some point, but probably not much this season. But that changed. Stutes joined the bullpen in April and quickly earned the trust of Manuel and pitching coach Rich Dubee, turning him into a steady late-inning reliever. And Worley became a fixture in the Phillies' rotation in June, giving the club five solid starters.

John Mayberry Jr: The Phillies entered the season with Ben Francisco, Domonic Brown and Mayberry competing for playing time in right field. It didn't work out the way the Phillies expected, which led to them acquiring Pence. But Mayberry eventually established himself as a consistent offensive threat. He took at-bats away from Raul Ibanez, and has made the Phillies' lineup a little more dangerous going down the stretch.

A Gold Glove: There are various modern metrics that measure a player's or team's defensive capabilities, but breaking it down simply, the Phillies have caught the ball this season. They entered September with the fewest errors in the Majors, and don't think the four aces didn't appreciate that. Fewer mistakes lead to fewer pitches and more innings for Halladay, Lee, Hamels and Oswalt, which also means a rested bullpen.

Resiliency: The Phillies had 15 players on the disabled list 20 times, but battled through it. Contreras replaced Lidge. Madson replaced Contreras. Wilson Valdez and Michael Martinez filled in for Utley, Rollins and Placido Polanco while they were out. Worley replaced Oswalt. Mayberry replaced Victorino. No matter the injury, somebody seemed to step up and the team didn't miss a beat.

The 10th Man: It makes a difference playing in a packed ballpark every night, which is what the Phillies have had this season. Fans could see the difference in early September. After looking flat in sparsely populated Sun Life Stadium in a pair of losses to the Marlins on Sept. 3-4, the Phillies returned to Citizens Bank Park energized and promptly beat the Braves, 9-0, on Sept. 5. It looked to some like the crowd provided a jolt. It probably did, and it probably will again come October.