First in a series examining the Phillies' potential offseason moves.

A shocked Hunter Pence left the visitors' clubhouse at Nationals Park after being traded from the Phillies to the San Francisco Giants on the final day of July.

"I don't think anyone really anticipated the season that has gone on this year," he said during his final interview with the Philadelphia media. "It was just the perfect storm of injuries, and things didn't go right for us."

It all ended up perfect for Pence, who celebrated a World Series title with his Giants teammates Sunday night after they completed a four-game sweep of the Tigers in chilly Detroit.

Meanwhile, back in Philadelphia, general manager Ruben Amaro Jr. has been back at the drawing board for more than a month trying to restore the Phillies' status as the best team in baseball.

"You have to give a lot of credit to the San Francisco Giants," Amaro said Monday. "They played like a team. They pitched great and they played great defense. All the offense in the world doesn't mean anything if you don't pitch and catch the baseball."

Amaro, nevertheless, will be in pursuit of some offensive help during this offseason, and his first chance to do so in free agency will come when the market opens Saturday.

Center field, manned primarily by John Mayberry Jr. after Shane Victorino was traded to the Los Angeles Dodgers the same day Pence went to the Giants, is the position most likely to be addressed in free agency.

"Right now, I think center field is a position that is going to have to be addressed externally," Amaro said.

Here is a look at the best free-agent options and some of the potential trade options:

Angel Pagan, San Francisco. Nobody's stock went up more during the 2012 season than the centerfielder the Giants acquired at last year's winter meetings from the New York Mets.

The pros: He would give the Phillies a switch-hitter with outstanding speed and baseball instincts at the top of the batting order. He'd also be an upgrade as a defensive centerfielder.

The cons: He did not have a good postseason at the plate. The Giants will likely want him back.

Michael Bourn, Atlanta. The Phillies' fourth-round pick in the 2003 draft became an all-star and Gold Glove winner with Houston and Atlanta and now the Phillies have a chance to get him back.

The pros: He's arguably the best defensive centerfielder in the league and can put a lot of stress on opposing teams when he is on base.

The cons: He struck out a career-high 155 times in 2012 and batted just .225 after the all-star break.

B.J. Upton, Tampa Bay. The older of the two Upton brothers appeared to be a superstar on the rise when the Phillies played Tampa Bay in the 2008 World Series. He has become somewhat of an enigma since, but potential always intrigues.

The pros: He is only 28 years old and has a rare combination of speed and power that makes scouts and general managers salivate.

The cons: His career-high 28 home runs were offset by a career-low .298 on-base percentage and career-high 169 strikeouts. A huge long-term contract would be a high risk.

Josh Hamilton, Texas. He is the best power hitter on the open market.

The pros: He has averaged 28 home runs and 101 RBIs with a .912 OPS during his five seasons with the Rangers.

The cons: He's a lefthanded hitter, and the Phillies need power from the other side. Under normal circumstances, teams would be lining up to give a talent like Hamilton the six-year, $100 million contract he is likely to seek. His history with substance abuse and injuries, however, makes him a huge risk.

Shane Victorino, L.A. Dodgers. You know him well.

The pros: He was a tremendous core player during the Phillies' five-year run of division titles, and his price tag probably went down based on his 2012 season.

The cons: The Phillies weren't happy with his defense or offense before they traded him.

Melky Cabrera, San Francisco. One failed drug test cost this man millions and millions of dollars.

The pros: He will be cheap, and he is a switch-hitter who was playing great before the failed drug test.

The cons: Was it Melky or was it the PEDs that performed so well in 2012?

Jacoby Ellsbury, Boston. The Red Sox centerfielder missed much of the 2012 season with a shoulder injury but is only a year removed from finishing second in the American League MVP voting.

The pros: When he's healthy, he is a superstar player with power and speed, and he is only 29 years old.

The cons: The price tag in terms of prospects will be high for a guy coming off a poor season.

Dexter Fowler, Colorado. It is hard to imagine a team would trade a 26-year-old centerfielder who hit .300 with a .389 on-base percentage, but there have been rumblings the Rockies would be willing to do so for quality pitching.

The pros: He would be the perfect leadoff hitter and is not eligible for free agency until 2016.

The cons: You have to think the price tag in terms of prospects will be very high.