This week's Power Rankings begin with a tip of the cap to several teams who are exceeding most preseason expectations placed upon them, and who could find themselves with higher positions in this space as soon as next week if they keep up this pace.
First up is the Athletics, who have won three straight, got a no-hitter from Sean Manaea vs. the Red Sox on Saturday, and have recorded wins in seven of their past eight games. The A's will continue their road series with the Rangers as one of four teams in the highly touted American League West with a winning record at 12-11, mere percentage points behind the 11-10 Mariners.

The Braves and Phillies deserve some love as well. Philadelphia is 9-1 at home and has won seven straight at Citizens Bank Park. The Phils' home record marks their best start to a season since they began the 1964 campaign by going 9-1 in their first 10 games at Connie Mack Stadium, and they will enter play on Tuesday in second place in the National League East, a half-game behind the Mets. The Braves, at 12-9, have sported a better record so far than the 10-13 Nationals, who were picked by most as the favorites to win the division.
Biggest jump: The Cardinals jumped six spots, from No. 13 to No. 7. Sure, they've played most of their games in the past week-and-a-half against the 4-18 Reds, but still, the numbers are notable. During a current stretch that produced a four-game sweep in Cincinnati, a rain-shortened two-game series split with the Cubs at Wrigley Field and a home sweep over the Reds, Cards starting pitchers have gone 7-1 with a 2.35 ERA, allowing 14 earned runs over 53 2/3 innings while walking 19 and striking out 51.

Biggest drop: The Pirates slipped six spots, from No. 11 to No. 17. The hot start has cooled in a big way. Since taking two of three over the Marlins, Pittsburgh has lost six of seven, including a four-game weekend sweep in Philadelphia. The Bucs are not hitting -- in those six losses, they scored just seven runs. Their only breakout game happened last Wednesday in a home game against the Rockies, when Pittsburgh scored 10.
Power Rankings Top 5
1. Red Sox (No. 1 last week)
The Red Sox had quite a weekend. They ended it with the best record in baseball still intact, but the Sox lost two in a row for the first time this season, with one of the losses a no-hitter by Manaea. Still, Boston is leading the Majors in many offensive categories, and its bullpen has been rock solid, stringing together 20 2/3 scoreless innings.

2. Astros (2)
The Astros opened their Seattle-Chicago road trip with a loss to the Mariners, marking their fifth defeat in six games. Then they reeled off six wins in a row, erasing the "slow start" speculation that had started to build around the defending World Series champs. In four games in Seattle, they outscored the Mariners, 21-6. Then they piled on 27 runs in three games in Chicago while holding the White Sox to two runs. Now comes a more challenging test: a long homestand with series against the Angels, A's and Yankees.
3. D-backs (5)
The D-backs, who have slid into the top of the Power Rankings among NL clubs, have won all seven series they've played so far in 2018; six against intradivision rivals. Based on early returns, this could be a breakout season for Patrick Corbin. The lefty struck out 11 Padres over six innings on Sunday and sports a 1.89 ERA and a 0.66 WHIP over five starts. He's walked six and struck out 48. Offensively, A.J. Pollock, the D-backs' primary cleanup hitter, has 16 RBIs and 14 extra-base hits through 20 games.

4. Mets (3)
The Mets have returned to normalcy after their red-hot start, but with a respectable 14-6 record even after series losses in the past week to the Nationals and the Braves, they remain in the Top 5 of the Power Rankings. New York has already made one major tweak, shifting Matt Harvey to the bullpen. Now the Mets have to figure out how to use him. High-leverage situations? Late innings? Harvey is not happy about his removal from the rotation, and it will be interesting to see how he responds when he's called upon from the 'pen.

5. Indians (9)
Their 12-8 record isn't necessarily eye-popping, but the Indians have turned it on lately due in part to impressive pitching performances. The Tribe has won nine of its past 12 games, allowing three runs or fewer in 11 of those 12 games. The Indians own the second-best ERA in the Majors at 2.57.
The rest of the Top 20
6. Angels (4)
7. Cardinals (13)
8. Nationals (8)
9. Yankees (6)
10. Dodgers (10)
11. Cubs (7)
12. Blue Jays (12)
13. Brewers (16)
14. Phillies (17)
15. Rockies (15)
16. Twins (14)
17. Pirates (11)
18. Braves (19)
19. Mariners (18)
20. Giants (20)