They have the most wins and the best record in baseball, and now the Giants have the No. 1 spot in our Power Rankings, too. San Francisco displaced its Bay Area rival in Oakland atop the rankings, bumping the Athletics down to No. 2. The Blue Jays continued their climb by moving up to No. 3, and the Brewers and Tigers round out our top-five at Nos. 4 and 5, respectively.
They're No. 1: Giants. Thirty-seven wins, a .649 winning percentage and a commanding 7½-game lead in the NL West: It all adds up to the No. 1 spot for San Francisco. The Giants are rolling right now, with eight wins in their last 10 games. That includes taking three of four from St. Louis over the weekend, finishing with a flourish in a 9-0 shutout on Sunday. San Francisco hasn't lost a series since May 5-7 against the Pirates and has gone 16-7 since then to open that huge lead in the division. Pablo Sandoval's awakening has helped key the Giants' recent run; after finishing April with a brutal .564 OPS, Sandoval rebounded to hit .318/.339/.542 with six homers and 19 RBIs in May, helping to make up for the loss of Brandon Belt to a broken thumb and a slump by Buster Posey.
Cellar Dweller: Diamondbacks. Arizona, which enters the new week on its seventh losing streak of at least three games this season, is back in its usual spot. While May was a much better month for the Diamondbacks (14-13 after a 9-19 March and April), Sunday's loss dropped Arizona to a season-worst 13 games under .500. Worse, A.J. Pollock, who hit .375/.427/.659 in May, broke his hand and is likely to miss two months. At 15 games back in the NL West and 7½ behind in the wild card, it's worth wondering how much longer the Diamondbacks will wait before selling off veteran parts. Players such as Aaron Hill, Martin Prado and Eric Chavez could see their names start popping up in trade rumors before long.
Biggest Riser: Red Sox. Boston's topsy-turvy season continues, as the Red Sox have followed up a 10-game losing streak by ripping off seven straight wins, including sweeps of Atlanta and Tampa Bay last week. That seven-game win streak is tied for the longest in MLB history following a double-digit losing skid, and it's helped the Red Sox climb out of the AL East cellar and go from No. 26 to No. 18 in our rankings. Top prospect Xander Bogaerts has been a big part of the resurgence, hitting .367/.457/.500 during the win streak to improve his overall line to a sparkling .296/.389/.427. Keep in mind, that's coming as a 21-year-old rookie shortstop. He'll be moving to third base with the recently re-signed Stephen Drew joining the team, but Bogaerts has already established himself as one of the team's top offensive weapons in his first full season in the majors.
Biggest Faller: Royals. Kansas City's lone highlight last week: Snapping Toronto's nine-game winning streak on Thursday. That was one of only two wins last week for the Royals, who fell from No. 15 to No. 22 in the rankings and fired their hitting coach to boot. Kansas City finished the month of May a disappointing 12-17 and is now four games under .500, not to mention stuck in last place in the AL Central. Will a new hitting coach improve things? Unless he can magically turn the lineup into nine Hank Aaron clones, probably not. The Royals' 24 homers as a team are the worst in the majors and just four more than the Orioles' Nelson Cruz has by himself.
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Brewers: After falling to a season-worst No. 8 in our rankings last week, Milwaukee is back up to No. 4 thanks to series wins over Baltimore and Chicago. The Brewers' NL Central lead had shrunk to as small as 1½ games over St. Louis, but Milwaukee now has that advantage back up to a more comfortable four games. The Brewers will get a good chance to open that lead even more with a week that pits them against the slumping Twins and the Pirates, against whom Milwaukee is 8-2 already this season.
Nationals: Is Washington going to disappoint for a second straight season? The Nationals are down to No. 14 in our rankings and below .500 overall despite taking two of three from Texas over the weekend, and now trail the Braves by 3½ games in the NL East. Atlanta has had Washington's number once again this year; after going 13-6 against the Nationals in 2013, the Braves are 5-1 against their division rivals so far this season. The two teams don't meet again until a four-game set in late June, but Washington will have a chance to gain some ground with six games upcoming against the last-place Phillies and struggling Padres before a big four-game series against the Giants in San Francisco.
Rays: This has been a throwback season for the Rays, who are doing everything they can to remind fans of the bad old Devil Rays days in St. Petersburg. The Rays are stuck in a six-game losing streak after getting swept by Toronto and Boston last week and are now a whopping 10½ games out in the AL East. The offense has scored just 16 runs during that skid and will be further tested by the loss of Wil Myers, who landed on the disabled list after suffering a wrist sprain during Friday's extra-innings loss to the Red Sox. Tampa Bay's .404 winning percentage is the worst in the American League — even Houston's (.414) is better — and its 23-34 record is the third-worst in all of baseball, ahead of just the Cubs and Diamondbacks.