If last week was an indicator of which of the elite teams have separated themselves from the pack, this week seems to be all about the clubs that were off to woefully slow starts and have suddenly sprung to life.

It wasn't long ago that the American League had only around a half-dozen teams with winning records. The National League was a little better, but not much. But now, entering Memorial Day competition, 18 of the 30 teams have records of .500 or better, and the 12 clubs that aren't leading their divisions are no worse than 2 1/2 games behind in the Wild Card standings.

Oakland is on such a hot streak -- nine wins in a row -- that we're almost tempted to suggest the Astros may have some competition in the American League West race. The Braves are six games over .500 and are chipping away at the Phillies' lead in the NL East. And still others -- the Rangers and Mets, specifically -- have scratched and clawed their way to the .500 mark.

Biggest jump: The A's made the biggest jump, possibly ever, since we started doing these rankings several years ago. They were not in the top 20 last week -- we had them No. 23 -- and now they're No. 12. The A's have won nine in a row, are three games over .500 and their starters have a 2.21 ERA (15 ER, 61 IP) over their past 10 games.

Biggest drop: The D-backs dropped five, from No. 11 to 16. They swept the Giants in San Francisco over the weekend, which helps, but it's not been a good month for Arizona. The D-backs' road trip began with a sweep by the Padres, and before that, they limped through a 4-6 homestand against the Braves, Pirates and Giants.

Power Rankings Top 5:

1) Astros (1 last week)

The Astros are on pace for 105 wins after taking two of three from the Red Sox at home over the weekend, and through a 22-game stretch that produced 17 wins, they hit 42 home runs, while outscoring opponents 132 to 71. They're going to be tested in the next several days and weeks, however, as injuries are starting to pile up. The biggest blow was losing George Springer to a hamstring injury that will sideline him for several weeks, if not longer. They're also playing without Jose Altuve (though he's due back soon), and they recently lost utility infielder Aledmys Diaz and catcher Max Stassi to leg injuries.

2) Dodgers (2)

The Dodgers have won nine of their past 11 games, scoring 64 runs in those contests. They piled on the Pirates over the weekend, outscoring them 28-11 in their three-game sweep at PNC Park. Cody Bellinger is on a hot streak, batting .357 (15-for-42) with four homers and 10 RBIs in his past 11 games.

3) Yankees (3)

They fell short of completing a perfect road trip with an extra-innings loss to the Royals on Sunday, but that didn't do much to detract from the Yankees' recent string of wins. It helps that they have been playing the Royals and Orioles a lot lately, but still, it's notable that they're 17-6 in May. Individually, Brett Gardner is hitting .464 (13-for-28) with six extra-base hits in his past eight games. Luke Voit, even with an 0-for-3 showing on Sunday, is hitting .347 (16-for-46) with three homers over his past 11 games.

4) Twins (6)

Standing ovation for the first-place, best-record-in-baseball, home run-mashing Minnesota Twins, who are turning the AL Central into a one-team race. They've won six in a row and have a double-digit lead over the Indians, the only other team in the division that doesn't have a losing record at 26-26. The Twins have hit 54 homers in May, and they're on pace for 324 this season. How ridiculous is this? The Yankees set the single-season home run record last year, with 267 long balls.

5) Cubs (5)

The Cubs have lost only two series since their season-opening road trip, and both of those losses have been against the Reds, in just under the past two weeks. Overall, the Cubs have been rolling -- their 3.82 ERA entering Sunday's game was the third-lowest in the NL, and they've performed well this month against the two teams that figure to be their biggest divisional competition -- they swept the Cardinals at home May 3-5, and took two of three a week later over the Brewers. The upcoming road trip could be interesting -- they go to Houston for three, followed by St. Louis for three.

The rest of the Top 20:

6. Rays (4)

7. Phillies (10)

8. Braves (13)

9. Red Sox (7)

10. Brewers (9)

11. Indians (12)

12. A’s (23)

13. Padres (15)

14. Cardinals (10)

15. Pirates (16)

16. D-backs (11)

17. Rockies (14)

18. Mets (20)

19. Rangers (24)

20. Nationals (17)