Catfish Hunter has started the most career games by a pitcher younger than 31, with 416 starts.

Interpreted as:

most regular-season games started by a player before age 31

	NAME	GS	G	W	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	Catfish Hunter C. Hunter	416	439	202	142	.587	3.10	1,874	167	40	1	3090.0	2,598	1,064	1,180	314	838	44	5	54	12,511	43	5.46	2.44	2.24	0.91	15.0	6.7	1.11	.242	3.44	7.57
2	Don Drysdale D. Drysdale	406	459	185	144	.562	2.98	2,226	152	39	6	3011.2	2,693	998	1,148	249	758	138	34	101	12,395	74	6.65	2.27	2.94	0.74	18.0	6.1	1.15	.271	3.43	8.05
3	Bert Blyleven B. Blyleven	402	407	167	148	.530	2.95	2,357	159	42	0	3000.2	2,699	984	1,103	215	810	75	3	49	12,274	66	7.07	2.43	2.91	0.64	19.2	6.6	1.17	.282	3.31	8.10
4	Walter Johnson W. Johnson	398	491	272	168	.618	0.96	2,408	350	77	20	3692.1	2,814		995	30	752	136	88			122	5.87	1.83	3.20	0.07		5.2	0.97	.252	2.43	6.86
5	Ken Holtzman K. Holtzman	370	382	165	135	.550	3.32	1,504	124	29	1	2607.0	2,467	961	1,100	215	789	41	4	56	10,889	84	5.19	2.72	1.91	0.74	13.8	7.2	1.25	.270	3.80	8.52
6	Felix Hernandez F. Hernandez	360	360	154	110	.583	3.16	2,270	25	11	0	2420.2	2,162	850	948	205	695	81	0	16	9,925	132	8.44	2.58	3.27	0.76	22.9	7.0	1.18	.293	3.52	8.04
7	Don Sutton D. Sutton	353	367	155	126	.552	3.02	1,913	110	40	3	2544.1	2,170	855	941	187	653	47	9	60	10,365	65	6.77	2.31	2.93	0.66	18.5	6.3	1.11	.262	3.33	7.68
8	Hal Newhouser H. Newhouser	353	431	191	140	.577	3.02	1,708	204	33	18	2784.1	2,482	934	1,099	119	1,177	17	61		11,772	60	5.52	3.80	1.45	0.38	14.5	10.0	1.31	.270	3.55	8.02
9	Robin Roberts R. Roberts	352	398	189	142	.571	3.26	1,433	217	30	23	2858.0	2,714	1,035	1,144	288	574	31	38		11,660	22	4.51	1.81	2.50	0.91	12.3	4.9	1.15	.260	3.60	8.55
10	Milt Pappas M. Pappas	351	397	156	122	.561	3.42	1,401	97	32	4	2392.1	2,222	908	1,001	219	688	53	30	61	9,890	83	5.27	2.59	2.04	0.82	14.2	7.0	1.22	.266	3.77	8.36
11	Vida Blue V. Blue	349	360	165	115	.589	3.13	1,697	131	33	2	2574.2	2,257	895	1,010	181	832	19	2	45	10,568	72	5.93	2.91	2.04	0.63	16.1	7.9	1.20	.265	3.53	7.89
12	Dave McNally D. McNally	347	373	165	103	.616	3.14	1,366	107	29	1	2393.2	2,140	834	908	203	709	60	6	44	9,797	52	5.14	2.67	1.93	0.76	13.9	7.2	1.19	.260	3.41	8.05
13	CC Sabathia	343	343	171	92	.650	3.51	1,921	32	12	0	2280.2	2,084	889	971	193	702	71	0	30	9,434	45	7.58	2.77	2.74	0.76	20.4	7.4	1.22	.289	3.83	8.22
14	Joe Coleman J. Coleman	340	428	137	135	.504	3.68	1,682	94	18	7	2464.1	2,305	1,008	1,146	225	958	87	41	61	10,486	110	6.14	3.50	1.76	0.82	16.0	9.1	1.32	.276	4.19	8.42
15	Rick Porcello R. Porcello	339	343	149	118	.558	4.36	1,507	10	3	0	2037.1	2,196	988	1,081	255	474	82	2	17	8,651	69	6.66	2.09	3.18	1.13	17.4	5.5	1.31	.306	4.78	9.70
16	Sam McDowell S. McDowell	337	396	138	126	.523	3.15	2,381	103	23	14	2402.0	1,871	840	957	157	1,247	59	31	68	10,183	135	8.92	4.67	1.91	0.59	23.4	12.2	1.30	.270	3.59	7.01
17	Greg Maddux G. Maddux	335	339	166	105	.613	2.85	1,660	75	21	0	2386.2	2,119	757	873	119	591	63	3	95	9,719	41	6.26	2.23	2.81	0.45	17.1	6.1	1.14	.274	3.29	7.99
18	Bob Friend B. Friend	334	421	135	158	.461	3.77	1,193	115	21	8	2487.1	2,619	1,042	1,202	210	675	26	42	70	10,547	37	4.32	2.44	1.77	0.76	11.3	6.4	1.32	.285	4.35	9.48
19	Steve Carlton S. Carlton	329	347	148	119	.554	3.10	1,916	145	31	1	2451.1	2,185	844	960	180	889	28	7	73	10,210	83	7.03	3.26	2.16	0.66	18.8	8.7	1.25	.279	3.52	8.02
20	Larry Dierker L. Dierker	329	355	139	123	.531	3.31	1,493	106	25	1	2332.1	2,129	857	948	184	710	50	9	45	9,655	103	5.76	2.74	2.10	0.71	15.5	7.4	1.22	.269	3.66	8.22
21	Bob Feller B. Feller	329	384	192	112	.632	3.05	2,108	213	34	20	2682.0	2,159	910	1,015	125	1,330	38	42		11,292	62	7.07	4.46	1.58	0.42	18.7	11.8	1.30	.264	3.41	7.24
22	Dennis Eckersley D. Eckersley	326	342	145	116	.556	3.59	1,486	99	20	3	2289.0	2,167	913	988	246	579	53	8	60	9,509	22	5.84	2.28	2.57	0.97	15.6	6.1	1.20	.269	3.88	8.52
23	Fernando Valenzuela F. Valenzuela	322	333	141	118	.544	3.34	1,764	107	29	2	2355.1	2,113	873	991	155	918	16	5	58	9,893	95	6.74	3.51	1.92	0.59	17.8	9.3	1.29	.278	3.79	8.07
24	Jim Palmer J. Palmer	321	347	174	93	.652	2.61	1,529	146	42	3	2504.2	2,038	727	815	173	853	25	10	32	10,180	64	5.49	3.07	1.79	0.62	15.0	8.4	1.15	.245	2.93	7.32
25	Rick Wise R. Wise	321	363	141	130	.520	3.57	1,245	113	25	0	2268.1	2,302	899	1,035	170	586	36	11	56	9,505	42	4.94	2.33	2.12	0.67	13.1	6.2	1.27	.285	4.11	9.13