Between the 1937 and 1946 seasons, the Philadelphia Phillies had the worst winning percentage by a team, winning 34.4 percent of the time.

	TEAM	W%	W	L	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	PA	TB	XBH	SH	GIDP	AVG	OBP	SLG	OPS
1	Phillies	.344	526	1,001	1,537	52,212	5,432	13,099	2,050	361	632	5,005	4,433	175	5,395	434	57,772	17,767	3,043	952	968	.251	.312	.340	.652
2	Athletics	.364	557	972	1,541	52,743	6,146	13,580	2,262	524	648	5,685	5,045	167	5,421	500	58,877	18,834	3,434	922	1,019	.257	.324	.357	.681
3	Browns	.439	671	859	1,549	53,362	6,952	13,990	2,527	472	858	6,518	5,664	163	5,955	396	60,163	20,035	3,857	974	882	.262	.335	.375	.710
4	Braves	.451	686	835	1,531	52,624	5,851	13,252	2,177	374	611	5,431	4,621	192	5,529	528	58,408	18,010	3,162	971	868	.252	.315	.342	.657
5	Senators	.471	720	810	1,542	53,782	6,807	14,440	2,407	649	487	6,244	5,355	218	5,042	921	60,222	19,606	3,543	867	860	.268	.337	.365	.702
6	Giants	.490	747	776	1,536	52,779	6,666	13,922	1,978	383	1,056	6,235	4,910	301	4,971	380	58,942	19,834	3,417	952	1,039	.264	.330	.376	.706
7	White Sox	.498	759	764	1,531	52,429	6,429	13,756	2,249	533	458	5,847	5,115	181	5,007	891	58,659	18,445	3,240	934	937	.262	.330	.352	.682
8	Pirates	.511	780	747	1,547	53,318	6,875	14,260	2,380	655	605	6,372	5,381	192	5,076	572	59,812	19,765	3,640	921	950	.267	.337	.371	.707
9	Indians	.517	790	738	1,540	52,876	6,775	13,947	2,619	646	824	6,298	5,297	166	5,860	589	59,327	20,330	4,089	988	899	.264	.333	.384	.717
10	Reds	.524	803	730	1,545	53,023	6,192	13,529	2,295	423	715	5,730	4,468	270	5,129	553	58,871	18,815	3,433	1,110	880	.255	.316	.355	.671
11	Cubs	.526	808	728	1,549	53,285	6,879	14,117	2,388	524	748	6,335	5,371	245	5,477	564	59,988	19,797	3,660	1,087	887	.265	.335	.372	.707
12	Dodgers	.544	834	699	1,551	53,433	7,168	14,194	2,561	585	639	6,585	5,727	204	5,308	647	60,431	19,842	3,785	1,067	854	.266	.339	.371	.710
13	Tigers	.545	838	701	1,552	53,510	7,436	14,330	2,440	517	1,024	6,888	5,898	185	5,694	627	60,555	20,876	3,981	962	1,026	.268	.343	.390	.733
14	Red Sox	.548	836	690	1,541	53,456	7,804	14,753	2,696	559	979	7,275	5,943	185	5,480	629	60,685	21,504	4,234	1,101	964	.276	.350	.402	.753
15	Cardinals	.608	934	602	1,560	54,597	7,448	15,082	2,740	620	847	6,919	4,859	223	5,218	582	60,894	21,603	4,207	1,215	764	.276	.338	.396	.734
16	Yankees	.618	948	585	1,546	53,160	8,063	14,197	2,364	618	1,353	7,574	6,408	318	5,950	651	60,679	21,856	4,335	793	898	.267	.349	.411	.761