George Zettlein has walked the worst walks per nine innings in a season, with 0.23 BB/9 in his rookie season in 1876.

Interpreted as:

worst bb/9 with a minimum of 1 IP per team game by a player in a season

	NAME	BB/9	SEASON	TM	G	W	L	W%	GS	ERA	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	ERA-	FIP	FIP-	H/9	PRAA
1	George Zettlein G. Zettlein	0.23	1876	PHI	28	4	20	.167	25	3.88	10	23	1	2	234.0	358	101	212	2	6		4		1,089	4	0.38	1.67	0.08	0.9	0.6	1.56		8.15	159	2.34	96	13.77	7.9
2	Cherokee Fisher C. Fisher	0.24	1876	CIN	28	4	20	.167	24	3.02	29	22	0	0	229.1	294	77	206	6	6		4		1,039	6	1.14	4.83	0.24	2.8	0.6	1.31		8.08	138	2.40	109	11.54	-10.3
3	George Bradley G. Bradley	0.28	1880	PRO	28	13	8	.619	20	1.38	54	16	4	2	196.0	158	30	66	2	6		7		757	7	2.48	9.00	0.09	7.1	0.8	0.84		3.03	60	2.21	96	7.26	0.6
4	Tommy Bond T. Bond	0.29	1876	HAR	45	31	13	.705	45	1.68	88	45	6	0	408.0	355	76	164	2	13		0		1,623	8	1.94	6.77	0.04	5.4	0.8	0.90		3.62	69	1.96	81	7.83	27.5
5	Tommy Bond T. Bond	0.39	1879	BOS	64	43	19	.694	64	1.96	155	59	11	0	555.1	543	121	206	8	24		1		2,189	13	2.51	6.46	0.13	7.1	1.1	1.02		3.34	79	2.50	101	8.80	-3.4
6	Bobby Mathews B. Mathews	0.42	1876	NYM	56	21	34	.382	56	2.86	37	55	2	0	516.0	693	164	395	8	24		0		2,327	3	0.65	1.54	0.14	1.6	1.0	1.39		6.89	128	2.43	109	12.09	-17.6
7	Carlos Silva C. Silva	0.43	2005	MIN	27	9	8	.529	27	3.44	71	2	0	0	188.1	212	72	83	25	9	3	0	2	749	0	3.39	7.89	1.19	9.5	1.2	1.17	.292	3.97	80	4.17	100	10.13	0.1
8	Guy Hecker G. Hecker	0.43	1882	LOU	13	6	6	.500	11	1.30	33	10	0	0	104.0	75	15	49	0	5		1		403	7	2.86	6.60	0.00	8.2	1.2	0.77		4.24	49	2.27	82	6.49	5.1
9	Dale Williams D. Williams	0.43	1876	CIN	9	1	8	.111	9	4.23	9	9	0	0	83.0	123	39	75	1	4		0		367	5	0.98	2.25	0.11	2.5	1.1	1.53		8.13	193	2.32	106	13.34	-2.9
10	Al Spalding A. Spalding	0.44	1876	CWS	61	47	12	.797	60	1.75	39	53	8	0	528.2	542	103	226	6	26		2		2,219	1	0.66	1.50	0.10	1.8	1.2	1.07		3.85	73	2.38	99	9.23	9
11	Pud Galvin P. Galvin	0.47	1879	BUF	66	37	27	.578	66	2.28	136	65	6	0	593.0	585	150	299	3	31		0		2,436	23	2.06	4.39	0.05	5.6	1.3	1.04		4.54	89	2.50	98	8.88	6.4
12	George Bradley G. Bradley	0.48	1879	TRO	54	13	40	.245	54	2.85	133	53	3	0	487.0	590	154	361	12	26		0		2,170	43	2.46	5.12	0.22	6.1	1.2	1.26		6.67	115	2.67	108	10.90	-12.6
13	Sam Weaver S. Weaver	0.49	1878	MIL	45	12	31	.279	43	1.95	95	39	1	0	383.0	371	83	214	2	21		2		1,589	25	2.23	4.52	0.05	6.0	1.3	1.02		5.03	79	2.27	92	8.72	15.6
14	Terry Larkin T. Larkin	0.53	1879	CWS	58	31	23	.574	58	2.44	142	57	4	0	513.1	514	139	277	5	30		0		2,176	20	2.49	4.73	0.09	6.5	1.4	1.06		4.86	95	2.49	97	9.01	9.3
15	Lady Baldwin L. Baldwin	0.53	1884	MIL	2	1	1	.500	2	2.65	21	2	0	0	17.0	7	5	5	0	1		0		61	0	11.12	21.00	0.00	34.4	1.6	0.47		2.65	20	0.98	9	3.71	8.2
16	Jim Devlin J. Devlin	0.54	1876	LOU	68	30	35	.462	68	1.56	122	66	5	0	622.0	566	108	309	3	37		0		2,568	14	1.77	3.30	0.04	4.8	1.4	0.97		4.47	62	2.08	82	8.19	50.7
17	Denny Driscoll D. Driscoll	0.54	1882	PIT	23	13	9	.591	23	1.21	59	23	0	0	201.0	162	27	73	0	12		0		799	7	2.64	4.92	0.00	7.4	1.5	0.87		3.27	45	2.36	84	7.25	10.2
18	Terry Larkin T. Larkin	0.55	1878	CWS	56	29	26	.527	56	2.24	163	56	1	0	506.0	511	126	288	4	31		0		2,105	37	2.90	5.26	0.07	7.7	1.5	1.07		5.12	94	2.18	92	9.09	15.3
19	John Ward J. Ward	0.55	1879	PRO	70	47	19	.712	60	2.15	239	58	2	1	587.0	571	140	270	5	36		10		2,425	29	3.66	6.64	0.08	9.9	1.5	1.03		4.14	89	2.22	92	8.75	7.9
20	Tommy Bond T. Bond	0.56	1878	BOS	59	40	19	.678	59	2.06	182	57	9	0	532.2	571	122	222	5	33		1		2,159	13	3.08	5.52	0.08	8.4	1.5	1.13		3.75	90	2.16	95	9.65	5.5
21	Candy Cummings C. Cummings	0.58	1876	HAR	24	16	8	.667	24	1.67	26	24	5	0	216.0	215	40	97	0	14		0		913	7	1.08	1.86	0.00	2.8	1.5	1.06		4.04	69	2.19	90	8.96	9.4
22	George Bradley G. Bradley	0.60	1876	STL	64	45	19	.703	64	1.23	103	63	16	0	573.0	470	78	229	3	38		0		2,269	34	1.62	2.71	0.05	4.5	1.7	0.89		3.60	58	2.14	101	7.38	-20.7
23	Henry Boyle H. Boyle	0.60	1884	SLU	19	15	3	.833	16	1.74	88	16	2	1	150.0	118	29	63	3	10		3		595	3	5.28	8.80	0.18	14.8	1.7	0.85		3.78	59	2.56	100	7.08	-1.1
24	George Bradley G. Bradley	0.61	1884	CNU	41	25	15	.625	38	2.71	168	36	3	0	342.0	350	103	203	7	23		3		1,437	12	4.42	7.30	0.18	11.7	1.6	1.09		5.34	85	2.76	99	9.21	5.2
25	Harry McCormick H. McCormick	0.61	1879	SYR	54	18	33	.353	54	2.99	96	49	5	0	457.1	517	152	291	3	31		4		1,975	31	1.89	3.10	0.06	4.9	1.6	1.20		5.73	126	2.61	110	10.17	-20.1