2015 MLB Relative Power Index (RPI),as of the games of September 12,2015

MLB RPI Rankings
RK	TEAM	RPI	W	L	PCT	SOS	PWR	RS	RA	EXPW-L	EXPWP
1	St. Louis Cardinals	.534	88	54	.620	.506	1	563	458	85-57	.602
2	Kansas City Royals	.530	84	57	.596	.508	2	638	554	80-61	.570
3	Pittsburgh Pirates	.523	85	56	.603	.496	3	607	515	82-59	.581
4	Chicago Cubs	.522	82	59	.582	.502	6	601	551	77-64	.543
5	Toronto Blue Jays	.521	82	60	.577	.502	4	790	587	91-51	.644
6	New York Yankees	.513	77	64	.546	.502	7	688	615	78-63	.556
7	Minnesota Twins	.513	73	68	.518	.511	13	606	619	69-72	.489
8	Los Angeles Dodgers	.512	81	60	.574	.492	5	586	514	80-61	.565
9	Houston Astros	.509	76	66	.535	.500	9	620	517	84-58	.590
10	New York Mets	.508	81	61	.570	.487	8	604	528	80-62	.567
11	Texas Rangers	.506	74	67	.525	.499	10	610	645	67-74	.472
12	Los Angeles Angels	.506	72	69	.511	.504	14	566	573	70-71	.494
13	Chicago White Sox	.505	67	73	.479	.513	21	553	594	65-75	.464
14	Cleveland Indians	.504	69	70	.496	.506	16	570	569	70-69	.501
15	Detroit Tigers	.501	64	76	.457	.515	23	606	710	59-81	.421
16	Tampa Bay Rays	.500	69	72	.489	.503	15	546	557	69-72	.490
17	San Francisco Giants	.499	74	68	.521	.492	12	609	538	80-62	.562
18	Baltimore Orioles	.499	68	73	.482	.505	17	624	599	73-68	.520
19	Seattle Mariners	.497	69	74	.483	.502	20	575	647	63-80	.441
20	Boston Red Sox	.495	67	74	.475	.502	22	660	680	68-73	.485
21	Washington Nationals	.493	71	70	.504	.489	11	616	570	76-65	.539
22	Arizona Diamondbacks	.490	68	74	.479	.494	19	639	624	73-69	.512
23	Milwaukee Brewers	.489	62	80	.437	.507	24	586	649	64-78	.449
24	San Diego Padres	.489	67	76	.469	.495	18	581	642	64-79	.450
25	Cincinnati Reds	.487	60	81	.426	.508	28	574	623	65-76	.459
26	Oakland Athletics	.487	61	81	.430	.505	25	592	595	71-71	.497
27	Miami Marlins	.473	61	81	.430	.488	27	525	583	64-78	.448
28	Colorado Rockies	.473	59	83	.415	.492	26	635	744	60-82	.421
29	Philadelphia Phillies	.463	55	88	.385	.489	29	548	737	51-92	.356
30	Atlanta Braves	.462	56	87	.392	.485	30	510	691	50-93	.353

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.