2015 MLB Relative Power Index (RPI),as of the games of September 19,2015

MLB RPI Rankings
RK	TEAM	RPI	W	L	PCT	SOS	PWR	RS	RA	EXPW-L	EXPWP
1	St. Louis Cardinals	.534	92	56	.622	.505	2	593	481	89-59	.603
2	Kansas City Royals	.525	86	62	.581	.507	3	663	590	83-65	.558
3	Chicago Cubs	.525	87	61	.588	.504	6	636	579	81-67	.547
4	Pittsburgh Pirates	.522	88	60	.595	.497	4	633	547	85-63	.572
5	Toronto Blue Jays	.519	85	63	.574	.500	1	818	604	96-52	.647
6	New York Yankees	.515	81	66	.551	.503	9	709	628	82-65	.560
7	Los Angeles Dodgers	.514	85	62	.578	.493	7	608	528	84-63	.570
8	Texas Rangers	.510	80	68	.541	.500	10	666	666	74-74	.500
9	Minnesota Twins	.508	75	73	.507	.509	12	641	652	73-75	.491
10	New York Mets	.507	84	64	.568	.487	5	626	559	82-66	.556
11	Los Angeles Angels	.506	76	72	.514	.504	13	595	607	73-75	.490
12	Houston Astros	.506	78	71	.523	.500	8	651	563	85-64	.572
13	Cleveland Indians	.504	73	74	.497	.506	14	611	599	75-72	.510
14	Detroit Tigers	.503	69	78	.469	.514	24	641	743	63-84	.427
15	Baltimore Orioles	.502	73	75	.493	.505	17	653	628	77-71	.520
16	Chicago White Sox	.501	70	77	.476	.510	21	583	648	66-81	.447
17	San Francisco Giants	.499	77	71	.520	.492	11	637	564	83-65	.561
18	Seattle Mariners	.498	72	77	.483	.503	18	597	667	66-83	.445
19	Tampa Bay Rays	.497	71	77	.480	.503	16	566	581	72-76	.487
20	Boston Red Sox	.496	70	77	.476	.502	20	685	701	72-75	.488
21	Washington Nationals	.495	77	71	.520	.487	15	659	591	82-66	.554
22	Arizona Diamondbacks	.491	71	77	.480	.495	19	662	646	76-72	.512
23	San Diego Padres	.488	69	80	.463	.496	22	608	681	66-83	.444
24	Cincinnati Reds	.487	63	84	.429	.507	27	605	660	67-80	.457
25	Oakland Athletics	.486	64	85	.430	.505	25	638	645	74-75	.495
26	Milwaukee Brewers	.485	62	86	.419	.507	23	610	684	66-82	.443
27	Colorado Rockies	.477	63	85	.426	.494	28	661	762	64-84	.429
28	Miami Marlins	.475	64	85	.430	.490	26	555	609	68-81	.454
29	Atlanta Braves	.464	59	90	.396	.487	29	525	719	52-97	.348
30	Philadelphia Phillies	.461	56	93	.376	.489	30	566	769	52-97	.351

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.