The Braves' rotation has gotten a few people talking thus far, including, but not limited to, the fact that their top four starters' ERA is better than the Phillies big 4 right now. Many fans of the Braves like to use that as a stepping stone to say that the Braves are better than the Phillies. It's hard to disagree with this results based analysis. A Philly blog did the analysis, and while I don't disagree with the premise of his argument for his team, I think he's got a few holes that he does not address or may be wrong about.
1) Sustainability: If you're looking at this from an outsider's perspective, you see the names of Halladay, Lee, Hamels and Oswalt. They are good-to-great pitchers, deserving their own designations, and they are going to be good-to-great when they are on the mound. Barring potential injuries, which you can say for any team in any sport, they are a known factor and they've proven themselves before. If you're looking at the Braves' rotation of Tim Hudson, Derek Lowe, Tommy Hanson, Jair Jurrjens, and Brandon Beachy, you may not know who three of those guys are. The former two are 10+ year vets and have their own track records of where they've come from and how they will most likely do in the future. However, looking at Hanson, Jurrjens, and Beachy, I wonder just how many baseball fans have no clue who they are or how long they've been in the majors. In my opinion, as well as many within Braves' fandom, these pitchers are above average pitchers capable of greatness in any single night. With limited track records, though, these three pitchers will continue to be looked at differently until proved otherwise. And this is a rather dangerous thought, because these three names are ones you should want to know about.
2) Pitching depth: It sounds pessimistic to say so, but every team will have injuries in some area of their team. Many teams carry extra arms so that they can have spot starters just in case one of their starters goes down. In some cases, you can see an injury coming from a dangerous overly dramatic pitching technique. In other cases, pitchers just break down and have to rest for a period of time. Within the Phillies rotation, they use Joe Blanton as their 5th starter, have Kyle Kendrick (who was their 5th starter last year because they had nobody else), and something called a Vance Worley as pitching depth in their minors. Yes, Kendrick has given the Braves some fits for some odd reason last year and this year, but overall last year, he gave the Phillies a very pedestrian 4.73 ERA in 10 starts. Vance Worley is by all accounts not a bad minor league pitcher, giving the Phillies something around a 3.50 ERA between AA and AAA last year. The guy is added pitching depth and that's all the Phillies can put on him at the moment, as his numbers do not seem to show him ready for any big league club right now.
Looking at the Braves' depth, their 5th starter is Brandon Beachy. Through 7 starts this year, he's given the Braves a sub-3.00 ERA and posting a little more than one strikeout per inning pitched. The Braves next option is Mike Minor, who started eight games last year for the big league club, but was shut down after exceeding his previous innings high by over 60 innings. In a pinch, the Braves would turn to him with no doubts that he could provide a good start or three without many ill-effects. Next in the pitching depth, I would say that you could turn to 20 year old Julio Teheran. Teheran made his major league debut against the Phillies on Saturday and proved that he had the stuff to make in the big leagues when the need for him arises. He did not fail to impress me with the stuff that he had, but his command just wasn't there for the debut. He will be a great option to turn to if one of the main starters needs a breather or goes down for an extended period of time. If you dared to look deeper in the Braves' minor leagues, you could look at 5th starter material in Rodrigo Lopez who actually started 33 games for the Diamondbacks last year.
Overall, if the Braves lost a starter for a week or three (or for the season?) they could bring in a starter who is ready and capable of filling in and giving quality innings. Philly fans themselves might find a hard time making up reasons for Kendrick or Worley to give good innings for an extended period of time, which is why the Braves show a club that is much more capable of handling an injury than the Phillies are.
My final thought about this debate, however, is that the Phillies big 4 will most likely have the better season. Their track record shows that they are capable of sustaining themselves if healthy. The Braves top 5 starters may very well be a step or two below the Phillies by the end of the season, but right now they are pitching to outduel each other every game and right now their ERA shows that they're doing better at keeping runs from crossing home.