If you believe in WAR -- the baseball acronym for wins above replacement -- then the best center fielder on the free-agent market is still available even after the Atlanta Braves signed B.J. Upton Wednesday.

Regardless of what source you use for WAR, Michael Bourn, the former Phillies fourth-round draft pick and Braves center fielder, was considered to be a far better player than Upton in 2012.

Bourn's FanGraphs WAR rating of 6.4 ranked 13th in all of baseball. The only National League center fielder that ranked ahead of him was Pittsburgh's Andrew McCutchen, whose 7.4 number was seventh in baseball.

Upton, by comparison, checked in at No. 61 with a 3.3 rating. That number was tied with four players, including former Phillies center fielder Shane Victorino, who is also on the free-agent market. Tied for 27th at 4.8 was Angel Pagan, another free-agent center fielder who is coming off an outstanding season with the World Series champion San Francisco Giants.

If you prefer BaseballReference's WAR rankings, Bourn still checked in ahead of all of the above free-agent center fielders with a 6.0 figure. Upton's BaseballReference WAR total in 2012 was 2.6. Victorino's WAR total slipped to 1.1 last season and has been on the decline the last two seasons. Pagan's total of 4.0 was the second best of his career and he could prove to be the best value of all the free-agent center fielders.

The primary reason for Bourn's high number is his ability to run down balls as a center fielder. He has been considered among the best -- and perhaps even the best -- defensive center fielder since becoming an everyday player with the Houston Astros in 2008.

Add in his ability as baseball's most prolific base stealer and the fact that he is an elite leadoff hitter, and it's understandable how his WAR ranks above all the other free-agent center fielders.

Does he have some warts? Yes, with the biggest one being that he strikes out a lot. He struck out a career-high 155 times last season, but still finished with a .346 on-base percentage from the leadoff spot, which ranked third in the National League among hitters with at least 400 plate appearances.

Bourn, who turns 30 next month, also is a left-handed hitter and the Phillies are more in need of right-handed bats, particularly ones that can infuse some power into the lineup. But Bourn hit ..273 with a .345 on-base percentage against lefties last season, which certainly qualifies as getting the job done.

Pagan, a switch-hitter, batted .271 with a .313 on-base percentage against lefties last season. He is 31 years old. Victorino, also a switch-hitter, batted .323 with a .388 on-base percentage against lefties last season, but hit only .229 with a .296 on-base percentage against righthanders. He turns 32 Friday and let us be the first to say happy birthday to the Flyin' Hawwaiian.

Bourn, with Scott Boras as his agent, is going to be the most expensive of the free-agent center fielders this offseason, but if you believe in WAR, he is also the best of the crop.