Walter Johnson has won the most career games by a pitcher younger than 30, with 249 wins.

Interpreted as:

pitcher with most regular-season wins prior to age 30

	NAME	W	L	W%	G	GS	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	249	155	.616	452	369	0.93	2,245	321	69	17	3366.1	2,574		924	28	683	127	78			114	6.00	1.83	3.29	0.07		5.2	0.97	.253	2.47	6.88
2	Hal Newhouser H. Newhouser	188	134	.584	419	342	2.96	1,691	201	33	18	2717.1	2,405	894	1,057	111	1,157	15	61		11,483	59	5.60	3.83	1.46	0.37	14.7	10.1	1.31	.270	3.50	7.97
3	Catfish Hunter C. Hunter	184	127	.592	402	379	3.06	1,696	146	38	1	2784.1	2,327	947	1,054	286	770	41	5	49	11,277	37	5.48	2.49	2.20	0.92	15.0	6.8	1.11	.241	3.41	7.52
4	Robin Roberts R. Roberts	179	119	.601	358	319	3.16	1,301	202	28	21	2599.1	2,453	914	1,014	245	530	30	33		10,584	22	4.50	1.84	2.45	0.85	12.3	5.0	1.15	.260	3.51	8.49
5	Bob Feller B. Feller	177	98	.644	348	301	2.99	2,000	198	34	20	2471.0	1,961	822	911	107	1,246	37	36		10,403	59	7.28	4.54	1.61	0.39	19.2	12.0	1.30	.264	3.32	7.14
6	Wes Ferrell W. Ferrell	175	115	.603	338	291	3.86	923	215	17	13	2404.2	2,571	1,031	1,219	110	925	20	39		10,543	28	3.45	3.46	1.00	0.41	8.8	8.8	1.45	.287	4.56	9.62
7	Don Drysdale D. Drysdale	170	129	.569	419	366	3.03	2,038	139	34	6	2727.0	2,428	918	1,052	232	709	127	34	91	11,232	67	6.73	2.34	2.87	0.77	18.1	6.3	1.15	.270	3.47	8.01
8	Waite Hoyt W. Hoyt	165	107	.607	392	290	3.48	774	166	18	30	2449.1	2,563	947	1,110	88	693	33	83		10,405	26	2.84	2.55	1.12	0.32	7.4	6.7	1.33	.281	4.08	9.42
9	Grover Alexander G. Alexander	160	75	.681	284	233	1.80	1,208	185	53	16	2101.1	1,765		681	42	499	46	47			18	5.17	2.14	2.42	0.18		6.0	1.08	.261	2.92	7.56
10	Mel Harder M. Harder	159	125	.560	419	286	3.82	833	134	16	23	2391.2	2,645	1,014	1,225	105	729	44	90		10,425	22	3.13	2.74	1.14	0.40	8.0	7.0	1.41	.291	4.61	9.95
11	Dwight Gooden D. Gooden	157	85	.649	305	303	3.10	1,875	67	23	1	2169.2	1,898	747	823	123	651	41	1	31	8,898	47	7.78	2.70	2.88	0.51	21.1	7.3	1.17	.286	3.41	7.87
12	Bert Blyleven B. Blyleven	156	141	.525	387	382	2.96	2,250	150	41	0	2841.1	2,554	933	1,051	206	770	70	3	48	11,630	63	7.13	2.44	2.92	0.65	19.3	6.6	1.17	.282	3.33	8.09
13	Milt Pappas M. Pappas	153	113	.575	373	331	3.35	1,343	96	32	4	2276.2	2,085	847	933	203	650	50	28	52	9,378	79	5.31	2.57	2.07	0.80	14.3	6.9	1.20	.264	3.69	8.24
14	Lefty Gomez L. Gomez	153	81	.654	296	252	3.22	1,235	149	24	10	2035.2	1,857	728	868	112	820	14	28		8,656	27	5.46	3.63	1.51	0.50	14.3	9.5	1.32	.269	3.84	8.21
15	Jim Palmer J. Palmer	152	80	.655	307	281	2.63	1,370	123	36	3	2189.2	1,783	639	714	153	769	17	10	27	8,924	59	5.63	3.16	1.78	0.63	15.4	8.6	1.17	.246	2.93	7.33
16	Greg Maddux G. Maddux	151	94	.616	304	300	2.88	1,488	70	20	0	2142.1	1,896	685	791	109	563	61	3	84	8,747	37	6.25	2.37	2.64	0.46	17.0	6.4	1.15	.274	3.32	7.97
17	Ken Holtzman K. Holtzman	151	124	.549	348	336	3.28	1,438	108	26	1	2360.1	2,202	861	992	197	719	40	4	54	9,848	74	5.48	2.74	2.00	0.75	14.6	7.3	1.24	.269	3.78	8.40
18	Vida Blue V. Blue	150	104	.591	330	319	3.09	1,570	121	32	2	2353.2	2,038	808	918	169	762	18	2	39	9,642	67	6.00	2.91	2.06	0.65	16.3	7.9	1.19	.262	3.51	7.79
19	CC Sabathia	148	84	.638	308	308	3.59	1,700	30	11	0	2027.1	1,854	808	879	180	635	63	0	25	8,391	42	7.55	2.82	2.68	0.80	20.3	7.6	1.23	.288	3.90	8.23
20	Dave McNally D. McNally	148	86	.632	335	309	3.13	1,279	90	25	1	2127.2	1,893	739	808	187	628	55	6	38	8,714	47	5.41	2.66	2.04	0.79	14.7	7.2	1.18	.260	3.42	8.01
21	Dizzy Dean D. Dean	147	80	.648	305	219	2.96	1,144	151	26	31	1909.2	1,846	628	736	89	430	27	76		7,908	12	5.39	2.03	2.66	0.42	14.5	5.4	1.19	.283	3.47	8.70
22	George Uhle G. Uhle	147	118	.555	350	267	3.91	761	167	16	16	2184.0	2,413		1,125	56	704	96	60		9,593	37	3.14	2.90	1.08	0.23	7.9	7.3	1.43	.296	4.64	9.94
23	Roger Clemens R. Clemens	146	68	.682	263	262	2.80	1,808	86	33	0	1956.1	1,630	608	677	125	534	48	0	34	7,911	46	8.32	2.46	3.39	0.58	22.9	6.8	1.11	.279	3.11	7.50
24	Tom Seaver T. Seaver	146	87	.627	283	278	2.47	1,856	133	29	1	2167.1	1,723	595	652	162	568	40	5	47	8,645	48	7.71	2.36	3.27	0.67	21.5	6.6	1.06	.259	2.71	7.15
25	Clayton Kershaw C. Kershaw	144	64	.692	292	290	2.36	2,120	25	15	0	1935.0	1,431	508	554	128	507	29	1	27	7,602	71	9.86	2.36	4.18	0.60	27.9	6.7	1.00	.270	2.58	6.66