2015 MLB Relative Power Index (RPI),as of the games of August 30,2015 from ESPN.GO.COM

MLB RPI Rankings
RK	TEAM	RPI	W	L	PCT	SOS	PWR	RS	RA	EXPW-L	EXPWP
1	St. Louis Cardinals	.540	84	46	.646	.504	1	524	387	84-46	.647
2	Kansas City Royals	.536	80	50	.615	.509	2	569	484	75-55	.580
3	Pittsburgh Pirates	.526	79	50	.612	.498	3	546	465	75-54	.580
4	Chicago Cubs	.521	74	55	.574	.503	4	527	498	68-61	.528
5	Toronto Blue Jays	.518	74	56	.569	.501	6	718	525	85-45	.652
6	New York Yankees	.515	72	57	.558	.501	5	627	550	73-56	.565
7	Houston Astros	.513	72	59	.550	.501	7	562	466	78-53	.593
8	Minnesota Twins	.511	67	63	.515	.509	16	564	571	64-66	.494
9	Texas Rangers	.508	68	61	.527	.502	11	575	594	62-67	.484
10	Los Angeles Dodgers	.508	72	57	.558	.491	8	527	464	73-56	.563
11	New York Mets	.506	72	58	.554	.490	9	530	477	72-58	.552
12	San Francisco Giants	.503	69	61	.531	.493	10	560	498	73-57	.558
13	Chicago White Sox	.503	61	68	.473	.513	20	493	551	57-72	.445
14	Cleveland Indians	.502	63	66	.488	.507	22	530	532	64-65	.498
15	Los Angeles Angels	.502	65	65	.500	.503	12	515	533	63-67	.483
16	Detroit Tigers	.502	60	70	.462	.515	18	567	640	57-73	.440
17	Tampa Bay Rays	.501	64	66	.492	.504	14	483	505	62-68	.478
18	Baltimore Orioles	.498	63	67	.485	.502	13	564	525	70-60	.536
19	Washington Nationals	.494	66	63	.512	.488	15	550	517	68-61	.531
20	Seattle Mariners	.493	61	70	.466	.502	23	509	600	55-76	.418
21	San Diego Padres	.493	63	67	.485	.496	19	529	576	59-71	.458
22	Boston Red Sox	.492	60	70	.462	.502	21	589	627	61-69	.469
23	Arizona Diamondbacks	.491	63	67	.485	.492	17	584	560	68-62	.521
24	Oakland Athletics	.488	57	74	.435	.506	25	538	526	67-64	.511
25	Milwaukee Brewers	.486	55	75	.423	.507	24	521	591	57-73	.437
26	Cincinnati Reds	.481	53	76	.411	.505	27	505	574	56-73	.436
27	Colorado Rockies	.472	52	76	.406	.494	28	573	678	53-75	.417
28	Atlanta Braves	.469	54	76	.415	.487	26	475	611	49-81	.377
29	Miami Marlins	.466	52	79	.397	.489	30	481	548	57-74	.435
30	Philadelphia Phillies	.466	52	79	.397	.489	29	501	663	48-83	.363

Glossary

• W: Wins
• L: Losses
• PCT: Winning percentage
• RPI: Relative Power Index+
• SOS: Strength of schedule

• PWR: ESPN Power Ranking
• RS: Runs scored
• RA: Runs allowed
• EXW-L: Expected W-L*
• EXWP: Expected winning percentage*

+The basic formula is 25% team winning percentage, 50% opponents' average winning percentage, and 25% opponents' opponents' average winning percentage.
*ExW-L and ExWP are derived from Bill James' Pythagorean theorem of baseball: Runs scored [squared] / (Runs scored [squared] + runs allowed [squared]). This formula was designed to relate a team's runs scored and runs allowed to its won-lost record.