Buck Gladmon has the lowest on-base percentage in a season, with an on-base percentage of .178 in his rookie season in 1884.

Interpreted as:

worst obp with a minimum of 3.1 PA per team game by a player in a season

	NAME	OBP	SEASON	TM	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	SLG	OPS	wRC	WRAA	wOBA	wRC+	BRAA
1	Buck Gladmon B. Gladmon	.178	1884	WSA	56	224	17	35	5	3	1		3	3				230	49	9					.156	.219	.397	16	-17.2	.183	51	-16.7
2	Bill Schenck B. Schenck	.216	1884	RIC	42	151	14	31	4	0	3		1	1				153	44	7					.205	.291	.507	16	-5.9	.230	71	-6.7
3	Sadie Houck S. Houck	.219	1886	TOT	113	455	43	92	11	1	0	31	6	4	28	29		465	105	12					.202	.231	.450	36	-31.7	.215	54	-31.9
4	Hal Lanier H. Lanier	.222	1968	SFG	151	486	37	100	14	1	0	27	12	0	57	2	2	518	116	15	14	6	0	17	.206	.239	.461	19	-28.9	.210	38	-31.5
5	George Creamer G. Creamer	.224	1884	PIT	98	339	38	62	8	5	0		16	2				357	80	13					.183	.236	.460	35	-17.4	.216	66	-18.3
6	Ed Kennedy E. Kennedy	.225	1884	NYM	103	378	49	72	6	2	1		16	1				395	85	9					.190	.225	.450	37	-20.5	.212	65	-20.8
7	Andres Thomas A. Thomas	.228	1989	ATL	141	554	41	118	18	0	13	57	12	0	62	3	3	571	175	31	1	4	3	17	.213	.316	.544	32	-30.6	.242	44	-35.3
8	John Kerins J. Kerins	.229	1884	IND	94	364	58	78	10	3	6		6	1				371	112	19					.214	.308	.537	44	-10.3	.243	79	-11.8
9	Harry Lyons H. Lyons	.230	1888	STL	123	499	66	97	10	5	4	63	20	3	47	36		522	129	19					.194	.259	.488	46	-22.3	.233	58	-30
10	Joe Dugan J. Dugan	.230	1918	PHA	121	411	26	80	11	3	3	34	16	3	55	4		447	106	17	17				.195	.258	.488	21	-22.3	.241	43	-26.5
11	Jack McGeachey J. McGeachey	.231	1888	IND	118	452	45	99	15	2	0	30	5	2	21	49		459	118	17					.219	.261	.492	40	-19.9	.232	60	-24.9
12	Charlie Levis C. Levis	.231	1884	TOT	91	386	59	87	11	4	5		3	0				389	121	20					.225	.313	.545	47	-10.1	.246	79	-11.8
13	Bones Ely B. Ely	.232	1901	TOT	110	411	29	87	12	5	0	44	9	2	42	11		435	109	17	13				.212	.265	.497	26	-30.8	.235	42	-34.3
14	Hobe Ferris H. Ferris	.232	1909	SLA	148	556	36	120	18	5	4	58	12	0	58	11		583	160	27	15				.216	.288	.520	37	-19.8	.254	64	-21.4
15	Fred Raymer F. Raymer	.232	1905	BSN	137	498	26	105	14	2	0	31	8	6	47	15		522	123	16	10				.211	.247	.479	29	-26.4	.233	46	-33.3
16	Germany Smith G. Smith	.233	1897	BKN	112	428	47	86	17	3	0	29	14	4	23	1		453	109	20	7				.201	.255	.488	22	-46.5	.235	36	-45.5
17	Jim Donnelly J. Donnelly	.234	1887	WSH	117	425	51	85	9	6	1	46	16	3	26	42		444	109	16					.200	.256	.491	35	-38.2	.233	50	-37.5
18	Bobby Lowe B. Lowe	.236	1904	TOT	141	507	47	105	14	6	0	40	17	2	44	15		541	131	20	15				.207	.258	.494	32	-22.8	.238	57	-24.5
19	Hunter Hill H. Hill	.236	1904	TOT	135	509	37	104	9	1	0	31	17	4	42	14		554	115	10	24				.204	.226	.462	28	-28.1	.225	52	-28.2
20	John Peltz J. Peltz	.236	1884	IND	106	393	40	86	13	17	3		7	2				402	142	33					.219	.361	.598	55	-4	.266	91	-5.5
21	Jim Levey J. Levey	.237	1933	SLA	141	529	43	103	10	4	2	36	26	3	68	4	6	567	127	16	9				.195	.240	.477	21	-44.5	.227	23	-58.3
22	Bill Kuehne B. Kuehne	.237	1886	PIT	117	481	73	98	16	17	1	48	19	2		26		502	151	34					.204	.314	.551	55	-18.1	.256	80	-14.8
23	Bill Greenwood B. Greenwood	.237	1884	BKN	92	385	52	83	8	3	3		10	1				396	106	14					.216	.275	.513	45	-13.2	.236	75	-14.7
24	Bill Hallman B. Hallman	.238	1901	TOT	128	464	48	86	13	5	0	41	28	4	42	13		525	109	18	29				.185	.235	.473	29	-39	.231	43	-39.5
25	Bobby Byrne B. Byrne	.238	1908	SLN	127	439	27	84	7	1	0	14	23	4	59	16		490	93	8	24				.191	.212	.450	23	-22.2	.225	48	-25.4