Cliff Lee's signing with the Phillies certainly impacts the Braves because they now must face the lefty and his team of pitching gods throughout the season. While I do not fully believe in player career stats against a team or other players because of so many variables, I do think it is worth noting in any case.
In three starts and 16 total innings against the Braves, Lee has a 5.06 ERA with no walks and 14 strikeouts. He has allowed 21 hits, four home runs and a .313 average against them. Alex Gonzalez has the most plate appearances against Lee with 14, and he is 4-12 with a home run. Chipper Jones is 2-8 with two doubles. The remaining starters with experience against him have five plate appearances or fewer, which is too small to even mention. Jason Heyward has yet to face him.
The signing of Lee immediately brought up debates of whether the 2011 Phillies front four could be the best in baseball history. Obviously, you cannot make this call until after the season plays out, but coming into the season on paper, it has a chance of happening. When these debates are made, the common comparable is the 1990s Braves rotations. For the sake of the Braves, I will use their three-year span of 1996-1998 in comparison to Philly's front four from the last three years.
Dave Cameron at Fangraphs already has this outlined, so I will basically summarize what he wrote and go deeper. Going by fWAR (Fangraphs Wins Above Replacement), this is how the two rotations compare:
Roy Halladay (21.5), Cliff Lee (20.9), Cole Hamels (11.9), Roy Oswalt (11.2)... Total: 65.5
Greg Maddux (23.7), John Smoltz (20.6), Tom Glavine (13.9), Steve Avery/Denny Neagle (11)... Total: 69.2
The fact that Cameron used two Braves rotations shows how insanely stacked the staff was during the 1990s. If you compare these two according to fWAR, the Braves have the advantage. Age and where they were in their careers also plays into this. Halladay was 31-33, Lee was 29-31, Hamels was 24-26, Oswalt was 30-32. Maddux was 30-32, Smoltz was 29-31, Glavine was 30-32, Avery was 26 and Neagle was 28-29. Ages are almost identical, and it shows both rotations were in their prime.
Beyond the Boxscore has a chart listing the rotations that featured four pitchers with 4+ rWAR (Baseball-Reference Wins Above Replacement), which the Phillies staff was able to do in 2010 if you include Lee with the other three. What to make of the chart is that the Phillies had two pitchers above five wins, which neither the 1997 nor the 1991 Braves staffs were able to do. The 1912 Red Sox and 1913 Giants both had three pitchers over five wins. It means that if Lee had put up his 2010 numbers with the Phillies, that rotation would have been ranked in the top 10 all time rotations. That also means if the Philly front four is able to repeat their numbers from a season ago, the NL East will feature one of the best rotations in the history of baseball again, but this time it is not in Atlanta.
Using these two resources, it is difficult to say whether the 1990s Braves rotations were really that much better than what Philly's front four is capable of. All you really need to know is the fact that people are comparing the two shows how truly talented the Phillies rotation will be. The Braves are in for a heck of a fight in 2011 and beyond.