Between the 1938 and 1947 seasons, the Philadelphia Phillies had the worst winning percentage by a team, winning 34.5 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	.345	527	1,001	1,537	52,044	5,297	12,971	2,002	376	589	4,881	4,419	185	5,348	428	57,607	17,492	2,967	959	1,087	.249	.310	.336	.646
2	Athletics	.379	581	951	1,543	52,713	6,080	13,493	2,202	516	615	5,617	5,067	186	5,427	442	58,962	18,572	3,333	996	1,136	.256	.323	.352	.676
3	Browns	.447	684	846	1,547	52,997	6,801	13,655	2,389	480	877	6,362	5,733	164	6,108	435	59,859	19,635	3,746	965	1,000	.258	.332	.370	.702
4	Braves	.455	693	830	1,533	52,753	5,973	13,431	2,242	375	633	5,542	4,694	188	5,324	541	58,622	18,322	3,250	987	998	.255	.318	.347	.665
5	Senators	.464	711	820	1,538	53,316	6,546	14,115	2,348	613	482	6,012	5,289	203	5,070	913	59,680	19,135	3,443	872	991	.265	.333	.359	.692
6	Giants	.481	733	792	1,539	52,793	6,764	13,884	1,947	390	1,166	6,348	4,992	293	5,049	364	59,004	20,109	3,503	926	1,153	.263	.330	.381	.711
7	White Sox	.488	743	780	1,532	52,426	6,202	13,628	2,180	498	444	5,640	5,057	177	5,088	912	58,539	18,136	3,122	879	1,079	.260	.327	.346	.673
8	Pirates	.495	756	771	1,549	53,192	6,915	14,095	2,373	613	714	6,422	5,524	205	5,280	570	59,823	19,836	3,700	902	1,086	.265	.336	.373	.709
9	Cubs	.510	784	752	1,550	53,241	6,635	13,953	2,366	498	723	6,113	5,302	242	5,559	515	59,817	19,484	3,587	1,032	999	.262	.332	.366	.698
10	Indians	.515	787	741	1,541	52,890	6,645	13,840	2,549	621	833	6,193	5,228	159	5,915	540	59,262	20,130	4,003	985	1,006	.262	.330	.381	.711
11	Reds	.535	820	713	1,544	53,092	6,261	13,572	2,322	407	737	5,800	4,570	267	5,073	546	59,062	18,919	3,466	1,133	977	.256	.318	.356	.674
12	Tigers	.542	834	705	1,555	53,270	7,215	14,082	2,365	497	977	6,678	6,003	176	5,545	590	60,438	20,372	3,839	989	1,156	.264	.341	.382	.723
13	Red Sox	.549	839	689	1,544	53,424	7,703	14,659	2,633	549	982	7,180	6,009	175	5,512	591	60,700	21,336	4,164	1,092	1,104	.274	.350	.399	.749
14	Dodgers	.565	866	668	1,551	53,387	7,326	14,221	2,544	582	685	6,750	5,990	213	5,286	666	60,663	19,984	3,811	1,073	941	.266	.343	.374	.717
15	Cardinals	.613	942	594	1,559	54,543	7,439	15,001	2,711	618	868	6,906	5,086	236	5,160	532	61,059	21,552	4,197	1,194	900	.275	.339	.395	.735
16	Yankees	.615	943	590	1,544	52,981	7,878	14,082	2,312	617	1,294	7,401	6,306	311	5,924	618	60,416	21,510	4,223	818	1,020	.266	.347	.406	.753