highest winning percentage by a pitcher in a season with at least 15 wins

Roy Face has the best win percentage with 15+ pitcher wins in a season, at .947 in 1959.

	NAME	W	W%	SEASON	TM	L	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	ERA-	FIP	FIP-	H/9	PRAA
1	Roy Face R. Face	18	.947	1959	PIT	1	57	0	2.70	69	0	0	10	93.1	91	28	29	5	25	1	47	8	380	4	6.65	2.41	2.76	0.48	18.2	6.6	1.24	.307	2.80	70	2.60	69	8.78	12.5
2	Tony Gonsolin T. Gonsolin	16	.941	2022	LAD	1	24	24	2.14	119	0	0	0	130.1	79	31	32	11	35	4	0	1	498	5	8.22	2.42	3.40	0.76	23.9	7.0	0.87	.207	2.21	55	3.27	81	5.46	10.8
3	Johnny Allen J. Allen	15	.938	1937	CLE	1	24	20	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
4	Greg Maddux G. Maddux	19	.905	1995	ATL	2	28	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	18	.900	1995	SEA	2	30	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	25	.893	1978	NYY	3	35	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	16	.889	1940	BKN	2	20	18	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	31	.886	1931	PHA	4	41	30	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	Aaron Sanchez A. Sanchez	15	.882	2016	TOR	2	30	30	3.00	161	0	0	0	192.0	161	64	69	15	63	5	0	0	790	5	7.55	2.95	2.56	0.70	20.4	8.0	1.17	.267	3.23	71	3.54	83	7.55	14.9
10	Bob Stanley B. Stanley	15	.882	1978	BOS	2	52	3	2.60	38	0	0	10	141.2	142	41	50	5	34	1	35	5	578	0	2.41	2.16	1.12	0.32	6.6	5.9	1.24	.274	3.18	65	3.24	83	9.02	10.6
11	Cliff Lee C. Lee	22	.880	2008	CLE	3	31	31	2.54	170	4	2	0	223.1	214	63	68	12	34	5	0	1	891	4	6.85	1.37	5.00	0.48	19.1	3.8	1.11	.301	2.74	59	2.82	67	8.62	35.4
12	Preacher Roe P. Roe	22	.880	1951	BKN	3	34	33	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
13	Clayton Kershaw C. Kershaw	21	.875	2014	LAD	3	27	27	1.77	239	6	2	0	198.1	139	39	42	9	31	2	0	0	749	7	10.85	1.41	7.71	0.41	31.9	4.1	0.86	.278	1.91	51	1.81	50	6.31	40.5
14	Max Scherzer M. Scherzer	21	.875	2013	DET	3	32	32	2.90	240	0	0	0	214.1	152	69	73	18	56	4	0	0	836	6	10.08	2.35	4.29	0.76	28.7	6.7	0.97	.259	3.07	72	2.74	69	6.38	29.2
15	Fred Goldsmith F. Goldsmith	21	.875	1880	CWS	3	26	24	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
16	Joe Wood J. Wood	34	.872	1912	BSA	5	43	38	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
17	Julio Urías J. Urías	20	.870	2021	LAD	3	32	32	2.96	195	0	0	0	185.2	151	61	67	19	38	7	0	3	745	2	9.45	1.84	5.13	0.92	26.2	5.1	1.02	.272	3.25	73	3.12	73	7.32	23.8
18	Roger Clemens R. Clemens	20	.870	2001	NYY	3	33	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
19	David Cone D. Cone	20	.870	1988	NYM	3	35	28	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
20	Zack Greinke Z. Greinke	19	.864	2015	LAD	3	32	32	1.66	200	1	0	0	222.2	148	41	43	14	40	5	0	1	843	7	8.08	1.62	5.00	0.57	23.7	4.7	0.84	.229	1.74	44	2.75	73	5.98	26.2
21	Orel Hershiser O. Hershiser	19	.864	1985	LAD	3	36	34	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
22	Whitey Ford W. Ford	25	.862	1961	NYY	4	39	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
23	Bill Donovan B. Donovan	25	.862	1907	DET	4	32	28	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
24	Chris Sale C. Sale	18	.857	2024	ATL	3	29	29	2.38	225	0	0	0	177.2	141	47	48	9	39	8	0	0	702	4	11.40	1.98	5.77	0.46	32.1	5.6	1.01	.314	2.43	57	2.08	52	7.14	38.1
25	Daisuke Matsuzaka D. Matsuzaka	18	.857	2008	BOS	3	29	29	2.90	154	0	0	0	167.2	128	54	58	12	94	7	0	1	716	5	8.27	5.05	1.64	0.64	21.5	13.1	1.32	.258	3.11	64	4.02	96	6.87	2.9