Bobby Witt has walked the best career walks per nine innings when starting 300+ games, with 5.02 BB/9.

Interpreted as:

highest career bb/9 by a player, min 300 gs

	NAME	BB/9	GS	G	W	L	W%	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	Bobby Witt B. Witt	5.02	397	430	142	157	.475	4.83	1,955	47	11	0	2465.0	2,493	1,324	1,449	252	1,375	39	13	37	11,003	128	7.14	1.42	0.92	17.8	12.5	1.57	.304	5.29	111	4.41	102	9.10	-26.2
2	Sam McDowell S. McDowell	4.74	346	425	141	134	.513	3.17	2,453	103	23	14	2492.1	1,948	879	999	164	1,312	59	39	74	10,587	140	8.86	1.87	0.59	23.2	12.4	1.31	.270	3.61	90	3.06	84	7.03	160.4
3	Nolan Ryan N. Ryan	4.67	773	807	324	292	.526	3.19	5,714	222	61	3	5386.0	3,923	1,911	2,178	321	2,795	158	13	78	22,575	277	9.55	2.04	0.54	25.3	12.4	1.25	.265	3.64	90	2.96	83	6.56	370.2
4	Allie Reynolds A. Reynolds	4.55	309	434	182	107	.630	3.30	1,423	137	36	48	2492.1	2,193	915	1,026	133	1,261	57	97		10,660	59	5.14	1.13	0.48	13.3	11.8	1.39	.265	3.70	90	3.64	99	7.92	2.9
5	Bump Hadley B. Hadley	4.41	355	528	161	165	.494	4.24	1,318	134	14	25	2945.2	2,980	1,389	1,609	167	1,442	63	108		13,016	72	4.03	0.91	0.51	10.1	11.1	1.50	.281	4.92	96	4.42	102	9.10	-27.9
6	Al Leiter A. Leiter	4.38	382	419	162	132	.551	3.80	1,974	16	10	2	2391.0	2,152	1,010	1,101	198	1,163	117	9	53	10,334	63	7.43	1.70	0.75	19.1	11.3	1.39	.284	4.14	90	4.09	95	8.10	63
7	Mark Baldwin M. Baldwin	4.20	328	346	154	165	.483	3.37	1,349	295	14	5	2802.1	2,695	1,050	1,816	81	1,307	123	19		12,470	221	4.33	1.03	0.26	10.8	10.5	1.43	.272	5.83	91	3.79	100	8.66	-0.9
8	Bob Feller B. Feller	4.15	484	570	266	162	.621	3.25	2,581	279	44	22	3827.0	3,271	1,384	1,557	224	1,764	60	52	6	16,180	69	6.07	1.46	0.53	16.0	10.9	1.32	.264	3.66	82	3.48	89	7.69	184.6
9	Bobo Newsom B. Newsom	4.15	483	600	211	222	.487	3.98	2,082	246	31	21	3759.1	3,769	1,664	1,908	206	1,732	61	71		16,467	60	4.98	1.20	0.49	12.6	10.5	1.46	.288	4.57	95	3.81	92	9.02	144.5
10	Hideo Nomo H. Nomo	4.13	318	323	123	109	.530	4.24	1,918	16	9	0	1976.1	1,768	932	993	251	908	38	2	31	8,462	109	8.73	2.11	1.14	22.7	10.7	1.35	.284	4.52	102	4.22	98	8.05	14.5
11	Carlos Zambrano C. Zambrano	4.13	302	354	132	91	.592	3.66	1,637	10	5	0	1959.0	1,709	797	879	161	898	102	11	41	8,389	58	7.52	1.82	0.74	19.5	10.7	1.33	.277	4.04	85	4.01	93	7.85	65.4
12	Ubaldo Jimenez U. Jimenez	4.08	315	329	114	117	.494	4.34	1,720	9	3	1	1870.0	1,757	901	968	186	848	78	4	31	8,094	93	8.28	2.03	0.90	21.3	10.5	1.39	.299	4.66	102	4.04	95	8.46	44.5
13	Amos Rusie A. Rusie	4.07	427	463	246	174	.586	3.07	1,950	393	30	5	3778.2	3,389	1,288	2,068	75	1,707	112	35		16,313	153	4.64	1.14	0.18	12.0	10.5	1.35	.266	4.93	78	3.71	92	8.07	124.3
14	Mike Torrez M. Torrez	4.05	458	494	185	160	.536	3.96	1,404	117	15	0	3043.2	3,043	1,340	1,501	223	1,371	59	13	84	13,179	103	4.15	1.02	0.66	10.7	10.4	1.45	.279	4.44	102	4.06	107	9.00	-86.3
15	Francisco Liriano F. Liriano	4.05	300	419	112	114	.496	4.15	1,815	3	1	1	1813.2	1,649	837	911	184	816	62	19	15	7,781	100	9.01	2.22	0.91	23.3	10.5	1.36	.299	4.52	101	3.88	95	8.18	39.3
16	Ryan Dempster R. Dempster	4.04	351	579	132	133	.498	4.35	2,075	11	3	87	2387.0	2,347	1,154	1,250	267	1,071	91	186	47	10,412	80	7.82	1.94	1.01	19.9	10.3	1.43	.301	4.71	103	4.25	100	8.85	-1.1
17	Bob Lemon B. Lemon	3.95	350	460	207	128	.618	3.23	1,277	188	31	22	2850.0	2,559	1,024	1,185	180	1,251	57	73	13	12,099	63	4.03	1.02	0.57	10.6	10.3	1.34	.255	3.74	84	3.79	99	8.08	7.5
18	Charlie Hough C. Hough	3.94	440	858	216	216	.500	3.75	2,362	107	13	61	3801.1	3,283	1,582	1,807	383	1,665	174	240	44	16,170	179	5.59	1.42	0.91	14.6	10.3	1.30	.250	4.28	95	4.28	109	7.77	-142.3
19	Lefty Gomez L. Gomez	3.94	320	368	189	102	.649	3.34	1,468	173	28	10	2503.0	2,290	930	1,091	138	1,095	19	31		10,729	39	5.28	1.34	0.50	13.7	10.2	1.35	.269	3.92	79	3.88	94	8.23	70.4
20	Mark Langston M. Langston	3.92	428	457	179	158	.531	3.97	2,464	81	18	0	2962.2	2,723	1,306	1,438	311	1,289	46	3	34	12,562	89	7.49	1.91	0.94	19.6	10.3	1.35	.285	4.37	93	3.93	91	8.27	120.6
21	Ken Hill K. Hill	3.89	315	332	117	109	.518	4.06	1,181	19	8	0	1973.0	1,938	891	977	162	852	47	4	43	8,520	78	5.39	1.39	0.74	13.9	10.0	1.41	.283	4.46	96	4.23	101	8.84	-7.4
22	Bob Buhl B. Buhl	3.84	369	457	166	132	.557	3.55	1,268	111	20	6	2587.0	2,446	1,019	1,162	238	1,105	37	38	52	11,045	68	4.41	1.15	0.83	11.5	10.0	1.37	.263	4.04	97	4.05	112	8.51	-134.8
23	Darryl Kile D. Kile	3.82	331	359	133	119	.528	4.12	1,668	28	9	0	2165.1	2,135	992	1,099	214	918	117	8	41	9,429	97	6.93	1.82	0.89	17.7	9.7	1.41	.295	4.57	96	4.24	100	8.87	0.6
24	Ice Box Chamberlain I. Box Chamberlain	3.80	301	321	157	120	.567	3.57	1,133	264	16	1	2521.2	2,446	999	1,560	63	1,065	113	19		11,097	149	4.04	1.06	0.22	10.2	9.6	1.39	.273	5.57	90	3.72	96	8.73	54
25	Tommy Bridges T. Bridges	3.80	362	424	194	138	.584	3.57	1,674	200	33	10	2826.1	2,675	1,122	1,321	181	1,192	35	47		12,165	59	5.33	1.40	0.58	13.8	9.8	1.37	.275	4.21	80	3.88	89	8.52	154.4