Between the 1981 and 1990 seasons, the Seattle Mariners had the lowest winning percentage by a team, winning 44.1 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	.441	691	875	1,567	53,237	6,512	13,624	2,459	320	1,338	6,155	4,946	346	8,397	1,133	625	59,362	20,737	4,117	423	410	319	1,185	.256	.321	.390	.710
2	Braves	.447	696	862	1,560	52,788	6,327	13,208	2,245	268	1,253	5,898	5,134	240	8,593	1,105	663	59,262	19,748	3,766	712	388	590	1,169	.250	.317	.374	.691
3	Indians	.454	708	853	1,563	53,473	6,883	14,130	2,359	324	1,188	6,425	5,009	275	7,884	1,196	586	59,768	20,701	3,871	505	506	361	1,227	.264	.328	.387	.715
4	Twins	.466	730	837	1,568	53,454	6,814	14,076	2,570	374	1,351	6,427	4,630	341	7,899	731	458	59,258	21,447	4,295	371	462	369	1,304	.263	.323	.401	.725
5	Rangers	.466	727	833	1,561	53,065	6,556	13,746	2,320	334	1,241	6,140	4,832	297	8,773	1,008	582	59,082	20,457	3,895	457	431	344	1,260	.259	.322	.386	.707
6	Pirates	.478	744	813	1,560	52,992	6,380	13,553	2,520	378	1,073	6,003	4,976	224	8,530	1,316	649	59,465	20,048	3,971	772	501	625	1,139	.256	.320	.378	.698
7	Cubs	.481	748	808	1,561	53,388	6,647	13,799	2,367	379	1,322	6,222	4,694	227	8,982	1,272	529	59,392	20,890	4,068	636	447	602	1,054	.258	.319	.391	.710
8	Padres	.488	764	803	1,568	53,183	6,279	13,587	2,153	366	1,010	5,835	4,823	206	8,559	1,330	648	59,439	19,502	3,529	813	414	697	1,165	.255	.318	.367	.684
9	Phillies	.492	769	794	1,566	52,979	6,551	13,412	2,317	377	1,249	6,165	5,405	291	9,433	1,272	550	59,715	20,230	3,943	609	431	615	1,168	.253	.323	.382	.705
10	Orioles	.497	776	784	1,561	52,900	6,865	13,512	2,288	218	1,587	6,493	5,707	259	8,431	685	414	59,741	20,997	4,093	444	431	387	1,369	.255	.328	.397	.725
11	Giants	.499	783	786	1,569	53,305	6,594	13,449	2,258	335	1,290	6,156	5,221	295	9,638	1,175	693	59,949	20,247	3,883	737	391	653	1,058	.252	.320	.380	.700
12	Reds	.501	783	781	1,565	52,945	6,417	13,392	2,413	314	1,184	5,951	5,113	251	8,921	1,509	608	59,447	19,985	3,911	701	437	601	1,147	.253	.319	.377	.697
13	White Sox	.501	782	780	1,563	52,956	6,875	13,665	2,360	381	1,313	6,464	4,738	363	8,593	1,192	551	59,116	20,726	4,054	582	477	409	1,131	.258	.321	.391	.712
14	Brewers	.506	792	772	1,565	53,725	7,129	14,206	2,480	376	1,298	6,713	4,694	298	7,808	1,109	541	59,768	21,332	4,154	533	518	404	1,179	.264	.324	.397	.721
15	Angels	.509	798	770	1,568	53,472	7,069	13,777	2,265	282	1,495	6,597	5,444	343	8,612	804	448	60,445	21,091	4,042	733	453	409	1,277	.258	.328	.394	.722
16	Astros	.511	801	767	1,568	53,080	6,144	13,353	2,287	403	950	5,748	4,877	227	8,446	1,432	653	59,369	19,296	3,640	731	454	630	995	.252	.315	.364	.678
17	Expos	.516	806	757	1,565	53,170	6,343	13,512	2,516	402	1,081	5,907	4,982	301	8,678	1,675	682	59,576	20,075	3,999	695	428	696	1,075	.254	.319	.378	.697
18	Royals	.516	804	755	1,560	53,322	6,707	14,099	2,588	452	1,200	6,355	4,548	280	8,244	1,269	516	58,947	21,191	4,240	354	443	406	1,206	.264	.323	.397	.720
19	Dodgers	.523	819	746	1,567	53,109	6,240	13,436	2,139	243	1,169	5,825	4,832	267	8,627	1,271	596	59,503	19,568	3,551	862	433	655	1,082	.253	.316	.368	.685
20	Yankees	.524	818	744	1,562	53,419	7,155	14,077	2,412	255	1,529	6,740	5,434	322	7,936	1,063	443	60,080	21,586	4,196	449	456	436	1,331	.264	.333	.404	.737
21	Athletics	.525	823	744	1,567	53,076	7,134	13,602	2,210	271	1,496	6,686	5,463	318	9,011	1,533	641	59,900	20,842	3,977	507	536	318	1,187	.256	.326	.393	.719
22	Cardinals	.527	821	738	1,562	52,792	6,435	13,594	2,322	481	731	5,969	5,313	213	8,313	2,149	734	59,577	19,071	3,534	795	464	587	1,060	.258	.325	.361	.687
23	Red Sox	.528	826	739	1,566	54,185	7,528	14,997	2,804	303	1,367	7,105	5,588	351	7,482	500	350	61,100	22,508	4,474	487	489	449	1,505	.277	.345	.415	.761
24	Tigers	.533	834	732	1,566	53,506	7,267	13,956	2,336	359	1,641	6,846	5,583	333	8,495	944	522	60,336	21,933	4,336	455	459	392	1,123	.261	.332	.410	.742
25	Blue Jays	.535	836	727	1,565	53,901	7,199	14,300	2,584	457	1,498	6,760	4,791	323	8,384	1,250	609	59,799	22,292	4,539	320	464	365	1,160	.265	.326	.414	.740