Power Rankings: Big shakeup and a new No. 1

At the quarter mark of the season, more than half of the teams have records of .500 or better, and in two divisions, four of five clubs are posting winning records.
Through play on Monday, 17 teams were at the .500 mark or higher. In two of three divisions in the National League -- the Central and East -- only the Marlins and Reds do not have more wins than losses.
While it's still very early, of all division races, the NL Central is shaping up to possibly be the wildest. Four teams are within a stone's throw of the lead, with the Cubs sitting at fourth place, four games over .500 and a two games behind the leading Brewers. A handful of percentage points are separating the top three clubs, one of which is Pittsburgh, which so far is making good on its promise that the trades of its two franchise players -- Andrew McCutchen and Gerrit Cole -- will pay off.
Biggest jump: Two teams jumped four spots: The Nationals, from No. 8 to No. 4, and the Pirates, from No. 17 to No. 13. In this space, let's focus on the Bucs, winners of six of their past eight games. They had a bit of a dud in their finale with the Giants on Sunday, losing 5-0, but before that, they were hitting .331 with 12 homers and 42 runs scored during a five-game winning streak. Meanwhile, Starling Marte is hitting .400 (14-for-35) five extra-base hits, eight RBIs and eight runs scored during his eight-game hitting streak.
Also notable: The Twins did not make the top 20 last week and are ranked 15th this week.
Biggest drop: The Cardinals and Blue Jays both dropped five spots. St. Louis seemed to be on the right track a week ago but has stumbled a bit lately, losing four of its past six, including the final two games of a four-game set with San Diego. The Cards will be without Carlos Martínez for a spell while the ace pitcher recovers from a lat strain, though it appears he'll only miss the minimum 10 days, and possibly only one start.
Power Rankings, Top 5
1. Yankees (2 last week)
The Yankees have won 19 of their past 22 games, scoring 132 runs -- an average of six per game -- over that span. Their 6-2 win over the A's on Sunday secured their best 40-game start since they won 31 of their first 40 in the 114-win season of 1998. Also, it looks like Giancarlo Stanton may have finally hit his stride -- over his past six games, he has nine hits in 23 at-bats with three homers and seven RBIs. His next hit will be the 1,000th of his career.

2. Astros (3)
The Astros had won five of seven heading into Monday, posting a 1.43 team ERA (10 ER, 63 IP) in that span. The staff has allowed just 51 baserunners while recording 70 strikeouts in that stretch.
Fun fact: Since Houston moved George Springer into the leadoff spot in May 2016, the team is 181-112.

3. Red Sox (1)
The Sox fell a couple of spots, partly due to dropping two of three to the Yankees last week. But they're far from losing their elite status. Among the many contributors is Mookie Betts, who would be a strong contender for the American League Most Valuable Player Award if the season ended today. The right fielder has scored a Major League-leading 43 runs and has scored at least one run in 27 of his past 34 games. Overall, Betts is slashing .362/.439/.766 with an OPS of 1.205.

4. Nationals (8)
The "What's wrong with the Nationals?" talk has, for now, been tabled. The Nats were a season-worst five games under .500 (11-16) on April 28, but since then, they've won 13 of 15 to go a season-best five games over .500. They've re-emerged just in time to realize the two teams they're looking up at in the standings -- the Braves and Phillies -- are no fluke. The NL East now boasts four teams with records above .500, with only the Marlins having a poor season so far.

5. Cubs (7)
They've lost two in a row -- a 5-3 loss to the White Sox on Sunday and a 6-5 loss to the Braves on Monday -- but still, the Cubs had a good week, sweeping the Marlins and taking two of three from the Sox. Over their past seven games, the Cubs have scored 58 runs. Offensively, two players stand out: Willson Contreras, who is batting .414 (12-for-29) with 12 RBIs over his past six games, and Anthony Rizzo, batting .309 (13-for-42) with 14 RBIs and 10 runs scored in 11 May games.

The rest of the Top 20

6. Diamondbacks (4 last week)
   
7. Indians (9)
   
8. Angels (6)
   
9. Braves (12)
   
10. Cardinals (5)
    
11. Brewers (10)
    
12. Phillies (15)
    
13. Pirates (17)
    
14. Rockies (11)
    
15. Twins (NR)
    
16. Mariners (16)
    
17. Mets (14)
    
18. Blue Jays (13)
    
19. Dodgers (19)
    
20. Giants (18)