Between the 1976 and 1985 seasons, the Seattle Mariners had the lowest winning percentage by a team, winning 40.9 percent of the time.

	TEAM	W%	W	L	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Mariners	.409	574	829	1,405	47,660	5,595	12,074	2,083	306	1,096	5,277	4,274	250	6,935	1,060	537	53,093	18,057	3,485	533	376	293	1,064	.253	.316	.379	.695
2	Blue Jays	.447	625	774	1,400	47,666	5,716	12,312	2,172	414	1,054	5,329	4,015	277	6,678	887	589	52,786	18,474	3,640	470	358	317	1,038	.258	.317	.388	.705
3	Mets	.454	708	853	1,564	52,761	5,892	13,159	2,134	340	918	5,451	4,880	251	8,682	1,204	665	59,006	18,727	3,392	684	430	572	1,198	.249	.314	.355	.669
4	Athletics	.458	716	849	1,565	52,554	6,434	13,140	2,038	312	1,262	5,979	5,053	250	8,302	1,767	834	59,002	19,588	3,612	655	490	351	1,105	.250	.316	.373	.689
5	Braves	.461	720	841	1,562	52,653	6,341	13,250	2,053	283	1,191	5,925	5,165	212	8,279	1,024	622	59,163	19,442	3,527	741	392	545	1,223	.252	.319	.369	.688
6	Indians	.462	716	835	1,552	52,826	6,736	13,998	2,160	352	991	6,281	5,463	269	6,755	1,124	692	59,734	19,835	3,503	626	550	363	1,363	.265	.334	.375	.709
7	Twins	.466	730	835	1,566	53,701	6,832	14,298	2,464	445	1,088	6,432	4,834	288	7,248	701	450	59,984	20,916	3,997	669	492	379	1,291	.266	.327	.389	.717
8	Giants	.468	734	834	1,568	52,780	6,151	13,121	2,095	342	1,106	5,738	5,357	210	8,589	1,089	614	59,580	19,218	3,543	806	427	589	1,179	.249	.318	.364	.682
9	Cubs	.471	734	825	1,563	53,342	6,482	13,763	2,340	379	1,115	6,048	4,936	245	8,302	1,038	559	59,675	20,206	3,834	699	453	589	1,147	.258	.321	.379	.700
10	Padres	.475	745	822	1,569	53,187	6,093	13,411	2,099	415	843	5,620	4,930	240	8,025	1,355	617	59,678	18,869	3,357	920	401	694	1,083	.252	.316	.355	.671
11	Rangers	.478	745	815	1,563	53,261	6,535	13,967	2,273	298	1,130	6,125	4,863	291	7,227	1,046	593	59,519	20,226	3,701	638	466	399	1,272	.262	.325	.380	.704
12	White Sox	.492	767	791	1,561	53,122	6,858	14,004	2,372	406	1,276	6,451	4,668	374	7,366	1,014	538	59,217	21,016	4,054	551	502	378	1,187	.264	.325	.396	.720
13	Angels	.495	775	791	1,566	53,032	6,920	13,723	2,216	291	1,312	6,471	5,462	377	8,102	888	581	60,129	20,457	3,819	785	473	402	1,310	.259	.330	.386	.715
14	Expos	.500	781	781	1,563	53,190	6,267	13,533	2,507	408	1,140	5,857	4,628	259	8,063	1,344	529	59,207	20,276	4,055	710	420	640	1,110	.254	.315	.381	.696
15	Brewers	.505	789	774	1,564	53,813	7,110	14,417	2,492	397	1,415	6,720	4,631	241	7,325	818	518	59,783	21,948	4,304	605	493	394	1,175	.268	.326	.408	.734
16	Astros	.512	803	766	1,569	53,177	6,135	13,675	2,262	526	790	5,730	4,743	204	7,698	1,485	673	59,356	19,359	3,578	788	444	636	1,024	.257	.318	.364	.682
17	Cardinals	.512	799	761	1,562	53,242	6,662	14,094	2,466	532	801	6,207	4,925	228	7,971	1,616	724	59,546	20,027	3,799	686	465	621	1,146	.265	.327	.376	.703
18	Pirates	.515	803	755	1,560	53,544	6,540	14,116	2,453	417	1,110	6,110	4,496	257	8,086	1,605	749	59,512	20,733	3,980	735	480	689	1,101	.264	.321	.387	.708
19	Reds	.525	821	742	1,565	52,989	6,743	13,728	2,473	370	1,176	6,289	5,643	214	8,676	1,434	585	60,039	20,469	4,019	709	484	630	1,168	.259	.330	.386	.716
20	Tigers	.528	826	738	1,565	53,670	7,140	14,273	2,282	418	1,490	6,731	5,195	281	7,852	936	562	60,133	21,861	4,190	494	493	356	1,221	.266	.331	.407	.738
21	Red Sox	.542	846	716	1,563	54,123	7,575	14,960	2,669	381	1,586	7,167	5,120	279	7,672	582	407	60,501	23,149	4,636	472	507	385	1,455	.276	.339	.428	.767
22	Phillies	.550	861	704	1,567	53,246	6,974	14,035	2,400	433	1,259	6,506	5,341	317	8,285	1,364	642	60,033	21,078	4,092	613	516	643	1,186	.264	.331	.396	.727
23	Royals	.551	860	701	1,562	53,805	7,175	14,678	2,682	573	1,113	6,757	4,553	304	6,936	1,645	656	59,658	21,845	4,368	443	553	439	1,163	.273	.330	.406	.736
24	Dodgers	.556	872	697	1,570	53,290	6,563	13,774	2,094	274	1,359	6,190	5,159	233	8,092	1,259	592	60,027	20,493	3,727	914	431	635	1,107	.258	.324	.385	.709
25	Orioles	.575	896	661	1,558	52,921	7,060	13,758	2,383	235	1,567	6,657	5,689	225	8,147	796	444	59,709	21,312	4,185	435	439	415	1,348	.260	.332	.403	.735