Jeff Samardzija

Oakland Athletics starting Jeff Samardzija delivers a pitch during Friday's game against the Seattle Mariners. (Ted S. Warren / Associated Press / July 11, 2014)

Jim Peltz ranks Major League Baseball's 30 teams. Last week’s rankings are in parentheses, Statistics are through Friday’s games.

1. OAKLAND: The A’s have baseball’s best winning percentage (.624) and have won seven of their last 10 games. (1)

2. DETROIT: Two days after scoring 14 runs against the Dodgers, the Tigers scored 16 runs to rout Kansas City. (2)

3. WASHINGTON: Nationals surge into contention with Atlanta for NL East lead after winning six of last 10 games. (8)

4. ANGELS: Pitcher C.J. Wilson goes on disabled list but Angels have won eight of last 10 games to keep pressure on Oakland. (5)

5. DODGERS: Clayton Kershaw wins eighth consecutive start after Dodgers drop two-game series in Detroit. (3)

6. BALTIMORE: Wei-Yin Chen earns ninth win and Orioles reach their 50 win in fewest games since 1997. (9)

7. ATLANTA: Closer Craig Kimbrel is tied for league lead in saves with 28 as the Braves stay near NL East lead. (6)

8. MILWAUKEE: The Brewers hit the skids, losing nine of 10 games, and barely maintain NL Central lead. (4)

9. SEATTLE: The Mariners are seven games over .500 but still eight games out of first place in tough AL West. (7)

10. ST. LOUIS: All-Star catcher Yadier Molina is out the next eight to 12 weeks with ligament tear in right thumb. (10)

11. SAN FRANCISCO: Tim Lincecum has won four in a row and given up one earned run in 30 1/3 innings. (15)

12. CINCINNATI: Second baseman Brandon Phillips (torn thumb ligament) joins teammate Joey Votto on DL. (14)

13. KANSAS CITY: Left fielder Alex Gordon (wrist) will miss the All-Star game but expects to avoid the disabled list. (12)

14. TORONTO: With four wins in last 10 games, the Blue Jays slip further behind first-place Baltimore in AL East. (13)

15. PITTSBURGH: As Brewers slide and Cardinals and Reds are hit by injuries, the Pirates are back in the NL Central race. (11)

16. N.Y. YANKEES: Stellar rookie Masahiro Tanaka misses All-Star game and goes on DL with elbow injury. (16)

17. CLEVELAND: The Indians win seven of last 10 games to reach .500 as they chase first-place Detroit. (17)

18. CHICAGO WHITE SOX: Chris Sale (8-1, 2.08 ERA) makes the AL All-Star team as chosen by fans’ online votes. (18)

19. MIAMI: Giancarlo Stanton reaches the All-Star break near the top of the NL in runs batted in (63) and home runs (21). (22)