Between the 1941 and 1950 seasons, the Philadelphia Phillies had the worst winning percentage by a team, winning 40.7 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	.407	625	911	1,547	52,602	5,675	13,243	2,041	421	763	5,252	4,640	221	5,663	446	58,326	18,415	3,225	863	1,198	.252	.315	.350	.665
2	Athletics	.414	636	900	1,544	52,387	6,065	13,291	2,084	495	564	5,607	5,596	200	5,158	387	59,204	18,057	3,143	1,021	1,355	.254	.328	.345	.673
3	Senators	.443	680	855	1,542	52,739	6,217	13,517	2,155	564	489	5,737	5,538	230	5,403	824	59,312	18,267	3,208	805	1,178	.256	.330	.346	.676
4	White Sox	.449	685	842	1,537	52,218	5,834	13,250	2,034	476	431	5,348	5,311	185	5,216	818	58,514	17,529	2,941	800	1,259	.254	.325	.336	.660
5	Browns	.450	689	842	1,543	52,404	6,577	13,289	2,295	471	862	6,133	5,930	168	6,352	425	59,459	19,112	3,628	957	1,181	.254	.331	.365	.696
6	Cubs	.472	725	812	1,549	53,022	6,350	13,706	2,250	462	826	5,860	5,094	236	5,878	480	59,297	19,358	3,538	945	1,114	.258	.326	.365	.691
7	Reds	.477	733	803	1,544	52,800	5,933	13,212	2,280	351	729	5,511	4,661	216	5,152	519	58,630	18,381	3,360	953	1,130	.250	.314	.348	.662
8	Pirates	.480	735	796	1,552	52,862	6,801	13,762	2,180	573	882	6,316	5,701	206	5,782	569	59,567	19,734	3,635	798	1,180	.260	.335	.373	.708
9	Giants	.481	738	796	1,549	52,908	6,944	13,729	1,942	421	1,278	6,518	5,413	275	5,339	398	59,444	20,347	3,641	848	1,212	.259	.331	.385	.716
10	Braves	.482	737	792	1,543	52,884	6,447	13,604	2,389	365	810	6,006	5,468	194	5,510	545	59,581	19,153	3,564	1,035	1,157	.257	.329	.362	.691
11	Indians	.524	803	728	1,544	52,787	6,612	13,731	2,329	550	965	6,202	5,542	198	5,872	470	59,537	20,055	3,844	1,010	1,200	.260	.333	.380	.713
12	Tigers	.545	839	700	1,556	53,131	6,904	13,931	2,276	472	862	6,397	6,168	183	5,305	444	60,521	19,737	3,610	1,039	1,376	.262	.341	.371	.712
13	Red Sox	.563	866	671	1,552	53,605	7,869	14,620	2,583	493	1,028	7,343	6,554	209	5,590	552	61,323	21,273	4,104	955	1,295	.273	.354	.397	.751
14	Dodgers	.581	895	646	1,553	53,517	7,687	14,389	2,537	523	890	7,058	6,142	225	5,349	793	60,983	20,642	3,950	1,099	1,065	.269	.347	.386	.732
15	Yankees	.611	939	599	1,544	52,866	7,728	14,097	2,227	638	1,212	7,246	6,248	286	5,634	519	60,236	21,236	4,077	836	1,196	.267	.347	.402	.749
16	Cardinals	.619	954	586	1,557	54,049	7,389	14,606	2,599	583	869	6,831	5,485	242	5,101	400	60,875	20,978	4,051	1,099	1,053	.270	.340	.388	.728