Walter Johnson had the most wins in starts when pitching in 30+ games, with 371 wins.

Interpreted as:

most regular-season wins in nb start by a player through 30 or more games

	NAME	W	GS	G	L	W%	ERA	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	H/9
1	Walter Johnson W. Johnson	371	654	654	242	.605	1.72	3,207	520	108	0	5447.0	4,516		1,736	89	1,276	190	0		21,802	140	5.30	2.11	2.51	0.15	14.7	5.9	1.06	.260	2.87	7.46
2	Warren Spahn W. Spahn	358	665	665	227	.612	3.08	2,501	382	63	0	5101.0	4,703	1,743	1,951	422	1,383	39	0	52	20,960	74	4.41	2.44	1.81	0.74	11.9	6.6	1.19	.258	3.44	8.30
3	Greg Maddux G. Maddux	355	740	740	226	.611	3.15	3,366	109	35	0	5001.0	4,717	1,750	1,974	351	996	137	0	177	20,388	70	6.06	1.79	3.38	0.63	16.5	4.9	1.14	.281	3.55	8.49
4	Roger Clemens R. Clemens	354	707	707	184	.658	3.12	4,671	118	46	0	4913.2	4,182	1,706	1,884	363	1,579	159	0	63	20,227	143	8.56	2.89	2.96	0.66	23.1	7.8	1.17	.284	3.45	7.66
5	Grover Alexander G. Alexander	350	600	600	193	.645	2.37	2,096	437	90	0	4978.1	4,654		1,742	156	887	66	0		20,045	33	3.79	1.60	2.36	0.28	10.5	4.4	1.11	.267	3.15	8.41
6	Steve Carlton S. Carlton	327	709	709	240	.577	3.20	4,104	254	55	0	5165.1	4,616	1,835	2,096	405	1,814	53	0	145	21,457	177	7.15	3.16	2.26	0.71	19.1	8.5	1.24	.279	3.65	8.04
7	Don Sutton D. Sutton	321	756	756	253	.559	3.27	3,545	178	58	0	5248.1	4,670	1,905	2,095	469	1,333	81	0	96	21,500	110	6.08	2.29	2.66	0.80	16.5	6.2	1.14	.261	3.59	8.01
8	Nolan Ryan N. Ryan	318	773	773	291	.522	3.18	5,654	222	61	0	5326.0	3,880	1,884	2,151	314	2,748	156	0	75	22,310	275	9.55	4.64	2.06	0.53	25.3	12.3	1.24	.265	3.63	6.56
9	Tom Seaver T. Seaver	310	647	647	203	.604	2.86	3,634	231	61	0	4776.1	3,961	1,517	1,670	378	1,387	76	0	115	19,337	123	6.85	2.61	2.62	0.71	18.8	7.2	1.12	.258	3.15	7.46
10	Tom Glavine T. Glavine	305	682	682	203	.600	3.54	2,607	56	25	0	4413.1	4,298	1,734	1,900	356	1,500	66	0	145	18,604	65	5.32	3.06	1.74	0.73	14.0	8.1	1.31	.280	3.87	8.76
11	Gaylord Perry G. Perry	305	690	690	252	.548	3.10	3,372	303	53	0	5156.2	4,762	1,778	2,045	382	1,314	101	0	144	21,140	150	5.89	2.29	2.57	0.67	16.0	6.2	1.18	.274	3.57	8.31
12	Phil Niekro P. Niekro	302	716	716	262	.535	3.37	3,181	245	45	0	5149.2	4,815	1,928	2,227	465	1,703	116	0	73	21,585	207	5.56	2.98	1.87	0.81	14.7	7.9	1.27	.270	3.89	8.42
13	Randy Johnson R. Johnson	301	603	603	166	.645	3.30	4,818	100	37	0	4103.0	3,320	1,504	1,692	408	1,491	188	0	37	16,937	109	10.57	3.27	3.23	0.89	28.4	8.8	1.17	.290	3.71	7.28
14	Early Wynn E. Wynn	287	611	611	232	.553	3.56	2,255	289	49	0	4398.2	4,135	1,742	1,981	330	1,713	62	0	32	18,704	50	4.61	3.50	1.32	0.68	12.1	9.2	1.33	.265	4.05	8.46
15	Bert Blyleven B. Blyleven	286	685	685	248	.536	3.31	3,694	242	60	0	4957.1	4,614	1,823	2,021	428	1,316	155	0	67	20,429	114	6.71	2.39	2.81	0.78	18.1	6.4	1.20	.282	3.67	8.38
16	Tommy John T. John	284	700	700	228	.555	3.35	2,191	162	46	0	4622.1	4,699	1,718	1,981	295	1,223	98	0	99	19,321	178	4.27	2.38	1.79	0.57	11.3	6.3	1.28	.284	3.86	9.15
17	Fergie Jenkins F. Jenkins	278	594	594	218	.560	3.32	3,082	267	49	0	4358.2	4,021	1,608	1,786	463	951	83	0	101	17,815	61	6.36	1.96	3.24	0.96	17.3	5.3	1.14	.269	3.69	8.30
18	Robin Roberts R. Roberts	275	609	609	240	.534	3.41	2,292	305	45	0	4567.1	4,467	1,733	1,915	498	872	54	0	63	18,724	32	4.52	1.72	2.63	0.98	12.2	4.7	1.17	.264	3.77	8.80
19	Mike Mussina M. Mussina	270	536	536	153	.638	3.68	2,812	57	23	0	3559.0	3,453	1,456	1,557	376	785	60	0	29	14,576	71	7.11	1.99	3.58	0.95	19.3	5.4	1.19	.292	3.94	8.73
20	Lefty Grove L. Grove	268	457	457	119	.693	3.08	2,013	298	35	0	3560.2	3,513	1,220	1,448	148	1,027	38	0		15,016	38	5.09	2.60	1.96	0.37	13.4	6.8	1.28	.285	3.66	8.88
21	Justin Verlander J. Verlander	266	555	555	158	.627	3.32	3,553	26	9	0	3567.2	3,046	1,317	1,428	371	1,004	121	0	28	14,607	99	8.96	2.53	3.54	0.94	24.3	6.9	1.14	.280	3.60	7.68
22	Red Ruffing R. Ruffing	264	538	538	212	.555	3.82	1,869	335	45	0	4132.2	4,094	1,755	2,016	249	1,463	51	0		17,623	44	4.07	3.19	1.28	0.54	10.6	8.3	1.34	.275	4.39	8.92
23	Jamie Moyer J. Moyer	262	638	638	206	.560	4.27	2,353	33	10	0	3947.1	4,107	1,872	2,020	509	1,104	142	0	64	16,812	52	5.36	2.52	2.13	1.16	14.0	6.6	1.32	.283	4.61	9.36
24	Jim Palmer J. Palmer	262	521	521	148	.639	2.80	2,142	211	53	0	3857.0	3,256	1,202	1,334	292	1,259	37	0	36	15,714	83	5.00	2.94	1.70	0.68	13.6	8.0	1.17	.247	3.11	7.60
25	Jim Kaat J. Kaat	260	625	625	217	.545	3.43	2,294	180	31	0	4137.2	4,203	1,579	1,850	366	955	115	0	77	17,336	116	4.99	2.08	2.40	0.80	13.2	5.5	1.25	.282	4.02	9.14