Atlanta's remarkable pitching and defense have held opponents to less than two runs per game, easily the best in baseball, while Oakland's powerful lineup has slugged its way to 96 runs, 15 more than any other big league ballclub.
The two have the best records, the most wins in their last 10 games and the best run differentials in the majors, making them obvious choices to lead SI.com's MLB Power Rankings for a second straight week.
As a reminder, a new quantitative formula has been devised to rank teams based purely on performance and not on subjectivity. Half of the ranking is determined by season record, with one quarter on recent play (which includes a small strength of schedule component) and one quarter on season run differential.
These rankings are not based on who has assembled the best rosters and will not (necessarily) predict who will win finish with the best record this season, but they will tell you who is playing the best baseball right now.
NOTE: All stats are updated through Wednesday, April 17.