The Washington Nationals had the highest run differential by a team in 2012, with a differential of 137 runs.

	TEAM	DIFF	SEASON	G	W%	W	L	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Nationals	137	2012	162	.605	98	64	5,615	731	1,468	301	25	194	688	479	41	1,325	105	35	6,221	2,401	520	50	36	43	110	.261	.322	.428	.750
2	Yankees	136	2012	162	.586	95	67	5,524	804	1,462	280	13	245	774	565	62	1,176	93	27	6,231	2,503	538	31	49	31	136	.265	.337	.453	.790
3	Rays	120	2012	162	.556	90	72	5,398	697	1,293	250	30	175	665	571	58	1,323	134	44	6,103	2,128	455	34	42	26	133	.240	.317	.394	.711
4	Cardinals	117	2012	162	.543	88	74	5,622	765	1,526	290	37	159	732	533	53	1,192	91	37	6,326	2,367	486	69	49	45	135	.271	.338	.421	.759
5	Rangers	101	2012	162	.574	93	69	5,590	808	1,526	303	32	200	780	478	57	1,103	91	44	6,214	2,493	535	36	53	44	121	.273	.334	.446	.780
6	Braves	100	2012	162	.580	94	68	5,425	700	1,341	263	30	149	660	567	34	1,289	101	32	6,125	2,111	442	53	46	37	108	.247	.320	.389	.709
7	Athletics	99	2012	162	.580	94	68	5,527	713	1,315	267	32	195	676	550	45	1,387	122	32	6,183	2,231	494	27	34	29	97	.238	.310	.404	.714
8	Reds	81	2012	162	.599	97	65	5,477	669	1,377	296	30	172	636	481	47	1,266	87	27	6,115	2,249	498	73	37	54	100	.251	.315	.411	.726
9	White Sox	72	2012	162	.525	85	77	5,518	748	1,409	228	29	211	726	461	65	1,203	109	43	6,111	2,328	468	31	36	24	112	.255	.318	.422	.740
10	Giants	69	2012	162	.580	94	68	5,558	718	1,495	287	57	103	675	483	29	1,097	118	39	6,200	2,205	447	69	61	44	114	.269	.327	.397	.724
11	Angels	68	2012	162	.549	89	73	5,536	767	1,518	273	22	187	732	449	47	1,113	134	33	6,120	2,396	482	47	41	29	138	.274	.332	.433	.764
12	Tigers	56	2012	162	.543	88	74	5,476	726	1,467	279	39	163	698	511	57	1,103	59	23	6,119	2,313	481	36	39	46	156	.268	.335	.422	.757
13	Diamondbacks	46	2012	162	.500	81	81	5,462	734	1,416	307	33	165	710	539	41	1,266	93	51	6,148	2,284	505	61	45	47	108	.259	.328	.418	.746
14	Brewers	43	2012	162	.512	83	79	5,557	776	1,442	300	39	202	741	466	90	1,240	158	39	6,224	2,426	541	76	35	35	111	.259	.325	.437	.762
15	Dodgers	40	2012	162	.531	86	76	5,438	637	1,369	269	23	116	607	481	52	1,156	104	44	6,091	2,032	408	82	38	49	139	.252	.317	.374	.690
16	Orioles	7	2012	162	.574	93	69	5,560	712	1,375	270	16	214	677	480	50	1,315	58	29	6,158	2,319	500	38	30	24	152	.247	.311	.417	.728
17	Phillies	4	2012	162	.500	81	81	5,544	684	1,414	271	28	158	659	454	63	1,094	116	23	6,172	2,215	457	72	39	41	114	.255	.317	.400	.716
18	Pirates	-23	2012	162	.488	79	83	5,412	651	1,313	241	37	170	620	444	51	1,354	73	52	6,014	2,138	448	62	45	32	98	.243	.304	.395	.699
19	Mariners	-32	2012	162	.463	75	87	5,494	619	1,285	241	27	149	584	466	30	1,259	104	35	6,057	2,027	417	32	35	21	95	.234	.296	.369	.665
20	Mets	-59	2012	162	.457	74	88	5,450	650	1,357	286	21	139	625	503	42	1,250	79	38	6,089	2,102	446	64	30	43	118	.249	.316	.386	.701
21	Padres	-59	2012	162	.469	76	86	5,422	651	1,339	272	43	121	610	539	54	1,238	155	46	6,112	2,060	436	63	34	36	100	.247	.319	.380	.699
22	Blue Jays	-68	2012	162	.451	73	89	5,487	716	1,346	247	22	198	677	473	55	1,251	123	41	6,093	2,231	467	33	45	29	109	.245	.309	.407	.716
23	Royals	-70	2012	162	.444	72	90	5,636	676	1,492	295	37	131	643	404	42	1,032	132	38	6,149	2,254	463	26	41	35	130	.265	.317	.400	.716
24	Red Sox	-72	2012	162	.426	69	93	5,604	734	1,459	339	16	165	695	428	45	1,197	97	31	6,166	2,325	520	34	55	27	105	.260	.315	.415	.730
25	Marlins	-115	2012	162	.426	69	93	5,437	609	1,327	261	39	137	576	484	35	1,228	149	41	6,056	2,077	437	60	40	46	114	.244	.308	.382	.690