2015 MLB Relative Power Index (RPI),as of the games of July 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	.539	65	37	.637	.507	1	406	300	66-36	.647
2	Kansas City Royals	.534	61	40	.604	.511	2	434	372	58-43	.576
3	Pittsburgh Pirates	.520	59	42	.584	.499	3	418	369	57-44	.562
4	Houston Astros	.515	58	45	.563	.500	7	456	378	61-42	.593
5	New York Yankees	.515	57	44	.564	.499	8	485	435	56-45	.554
6	Chicago Cubs	.515	54	47	.535	.509	10	388	387	51-50	.501
7	Minnesota Twins	.512	53	48	.525	.507	11	433	428	51-50	.506
8	Los Angeles Dodgers	.509	57	45	.559	.493	4	423	362	59-43	.577
9	Los Angeles Angels	.509	55	46	.545	.498	6	431	381	57-44	.561
10	Detroit Tigers	.507	50	52	.490	.512	14	455	488	47-55	.465
11	Chicago White Sox	.504	49	51	.490	.509	20	366	418	43-57	.434
12	San Francisco Giants	.503	56	45	.554	.485	5	437	383	57-44	.566
13	Washington Nationals	.502	54	46	.540	.489	9	419	386	54-46	.541
14	San Diego Padres	.500	49	53	.480	.507	19	393	446	45-57	.437
15	New York Mets	.499	52	50	.510	.495	13	363	370	50-52	.490
16	Baltimore Orioles	.499	51	50	.505	.497	16	440	393	56-45	.556
17	Toronto Blue Jays	.498	52	51	.505	.495	12	543	440	62-41	.604
18	Texas Rangers	.497	49	52	.485	.501	17	442	486	46-55	.453
19	Cleveland Indians	.497	47	54	.465	.508	18	395	431	46-55	.456
20	Tampa Bay Rays	.497	51	52	.495	.498	15	367	380	50-53	.483
21	Arizona Diamondbacks	.494	49	51	.490	.496	22	442	431	51-49	.513
22	Seattle Mariners	.491	46	57	.447	.506	23	373	438	43-60	.420
23	Milwaukee Brewers	.490	44	59	.427	.511	27	405	454	46-57	.443
24	Cincinnati Reds	.490	46	54	.460	.500	25	405	444	45-55	.454
25	Oakland Athletics	.489	45	58	.437	.506	24	431	397	56-47	.541
26	Boston Red Sox	.482	45	58	.437	.497	26	425	495	44-59	.424
27	Atlanta Braves	.479	46	56	.451	.488	21	374	428	44-58	.433
28	Colorado Rockies	.477	43	57	.430	.493	28	461	518	44-56	.442
29	Miami Marlins	.473	42	60	.412	.493	29	364	395	47-55	.459
30	Philadelphia Phillies	.465	39	64	.379	.494	30	365	506	35-68	.342

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.