highest winning percentage by a pitcher in a season with a minimum of 16 starts before 2004

Before 2004, Johnny Allen had the highest win percentage with 16+ starts in a season, at .938 in 1937.

	NAME	W%	GS	SEASON	TM	W	L	G	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	ERA-	FIP	FIP-	H/9	PRAA
1	Johnny Allen J. Allen	.938	20	1937	CLE	15	1	24	2.55	87	14	0	0	173.0	157	49	55	4	60	5	4		713	2	4.53	3.12	1.45	0.21	12.2	8.4	1.25	.275	2.86	56	3.46	77	8.17	19.8
2	Jim Nash J. Nash	.923	17	1966	KCA	12	1	18	2.06	98	5	0	1	127.0	95	29	32	6	47	0	1	3	516	4	6.94	3.33	2.09	0.43	19.0	9.1	1.12	.244	2.27	59	2.74	75	6.73	12.4
3	Perry Werden P. Werden	.923	16	1884	SLU	12	1	16	1.97	51	12	1	0	141.1	113	31	61	1	22		0		575	5	3.25	1.40	2.32	0.06	8.9	3.8	0.96		3.88	67	3.11	121	7.20	-10
4	Greg Maddux G. Maddux	.905	28	1995	ATL	19	2	28	1.63	181	10	3	0	209.2	147	38	39	8	23	4	0	3	785	1	7.77	0.99	7.87	0.34	23.1	2.9	0.81	.244	1.67	39	2.25	52	6.31	46.9
5	Randy Johnson R. Johnson	.900	30	1995	SEA	18	2	30	2.48	294	6	3	0	214.1	159	59	65	12	65	6	0	1	866	5	12.35	2.73	4.52	0.50	33.9	7.5	1.05	.301	2.73	53	2.08	44	6.68	62
6	Ron Guidry R. Guidry	.893	35	1978	NYY	25	3	35	1.74	248	16	9	0	273.2	187	53	61	13	72	1	0	1	1,057	7	8.16	2.37	3.44	0.43	23.5	6.8	0.95	.241	2.01	48	2.18	58	6.15	48.5
7	Freddie Fitzsimmons F. Fitzsimmons	.889	18	1940	BKN	16	2	20	2.81	35	11	4	1	134.1	120	42	43	5	25	1	2		543	2	2.34	1.67	1.40	0.33	6.4	4.6	1.08	.241	2.88	72	3.38	85	8.04	8.9
8	Lefty Grove L. Grove	.886	30	1931	PHA	31	4	41	2.06	175	27	4	5	288.2	249	66	84	10	62	1	10		1,160	2	5.46	1.93	2.82	0.31	15.1	5.3	1.08	.262	2.62	47	3.01	70	7.76	40.8
9	Preacher Roe P. Roe	.880	33	1951	BKN	22	3	34	3.04	113	19	2	0	257.2	247	87	91	30	64	0	1		1,031	2	3.95	2.24	1.77	1.05	11.0	6.2	1.21	.263	3.18	76	3.86	94	8.63	6.8
10	Tom Seaver T. Seaver	.875	23	1981	CIN	14	2	23	2.54	87	6	1	0	166.1	120	47	51	10	66	3	0	8	671	5	4.71	3.57	1.32	0.54	13.0	9.8	1.12	.218	2.76	72	3.58	104	6.49	-2.2
11	Fred Goldsmith F. Goldsmith	.875	24	1880	CWS	21	3	26	1.75	90	22	4	1	210.1	189	41	80	2	18		1		837	10	3.85	0.77	5.00	0.09	10.8	2.2	0.98		3.42	72	2.06	84	8.09	10.4
12	Joe Wood J. Wood	.872	38	1912	BSA	34	5	43	1.91	258	35	10	1	344.0	267	73	104	2	82	12	5		1,328	7	6.75	2.15	3.15	0.05	19.4	6.2	1.01	.272	2.72	58	2.25	71	6.99	35.1
13	Roger Clemens R. Clemens	.870	33	2001	NYY	20	3	33	3.51	213	0	0	0	220.1	205	86	94	19	72	5	0	1	918	14	8.70	2.94	2.96	0.78	23.2	7.8	1.26	.305	3.84	80	3.28	74	8.37	28.1
14	David Cone D. Cone	.870	28	1988	NYM	20	3	35	2.22	213	8	4	0	231.1	178	57	67	10	80	4	0	7	936	10	8.29	3.11	2.66	0.39	22.8	8.5	1.12	.267	2.61	68	2.57	75	6.93	22.5
15	Orel Hershiser O. Hershiser	.864	34	1985	LAD	19	3	36	2.03	157	9	5	0	239.2	179	54	72	8	68	6	1	5	953	5	5.90	2.55	2.31	0.30	16.5	7.1	1.03	.239	2.70	59	2.73	77	6.72	22.1
16	Whitey Ford W. Ford	.862	39	1961	NYY	25	4	39	3.21	209	11	3	0	283.0	242	101	108	23	92	1	0	3	1,159	8	6.65	2.93	2.27	0.73	18.0	7.9	1.18	.263	3.43	85	3.14	82	7.70	22.7
17	Bill Donovan B. Donovan	.862	28	1907	DET	25	4	32	2.19	123	27	3	1	271.0	222	66	96	3	82	8	4		1,073	2	4.08	2.72	1.50	0.10	11.5	7.6	1.12	.256	3.19	84	2.41	98	7.37	2
18	Jason Bere J. Bere	.857	24	1994	CWS	12	2	24	3.81	127	0	0	0	141.2	119	60	65	17	80	1	0	0	608	2	8.07	5.08	1.59	1.08	20.9	13.2	1.40	.266	4.13	83	4.61	98	7.56	1.2
19	Roger Clemens R. Clemens	.857	33	1986	BOS	24	4	33	2.48	238	10	1	0	254.0	179	70	77	21	67	4	0	0	997	11	8.43	2.37	3.55	0.74	23.9	6.7	0.97	.237	2.73	58	2.80	69	6.34	36.3
20	Dwight Gooden D. Gooden	.857	35	1985	NYM	24	4	35	1.53	268	16	8	0	276.2	198	47	51	13	69	2	0	4	1,065	6	8.72	2.24	3.88	0.42	25.2	6.5	0.97	.259	1.66	44	2.12	59	6.44	45.6
21	Mike Nagy M. Nagy	.857	28	1969	BOS	12	2	33	3.11	84	7	1	0	196.2	183	68	84	10	106	11	2	3	870	6	3.84	4.85	0.79	0.46	9.7	12.2	1.47	.263	3.84	80	4.09	102	8.37	-0.6
22	Pedro Martinez P. Martinez	.852	29	1999	BOS	23	4	31	2.07	313	5	1	0	213.1	160	49	56	9	37	9	1	1	835	6	13.20	1.56	8.46	0.38	37.5	4.4	0.92	.323	2.36	42	1.38	30	6.75	79.4
23	John Smoltz J. Smoltz	.850	26	1998	ATL	17	3	26	2.90	173	2	2	0	167.2	145	54	58	10	44	4	0	2	681	3	9.29	2.36	3.93	0.54	25.4	6.5	1.13	.300	3.11	69	2.70	63	7.78	29.2
24	Chief Bender C. Bender	.850	23	1914	PHA	17	3	28	2.26	107	14	7	2	179.0	159	45	49	4	55	1	4		718	3	5.38	2.77	1.95	0.20	14.9	7.7	1.20	.281	2.46	84	2.47	88	7.99	6.5
25	Lefty Grove L. Grove	.848	32	1930	PHA	28	5	50	2.54	209	22	2	9	291.0	273	82	101	8	60	5	17		1,191	2	6.46	1.86	3.48	0.25	17.5	5.0	1.14	.292	3.12	53	3.09	64	8.44	55.6