highest winning percentage by a pitcher in a season with at least 20 wins

Ron Guidry has the highest win percentage with 20+ pitcher wins in a season, at .893 in 1978.

	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	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
2	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
3	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
4	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
5	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
6	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
7	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
8	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
9	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
10	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
11	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
12	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
13	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
14	Roger Clemens R. Clemens	24	.857	1986	BOS	4	33	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
15	Dwight Gooden D. Gooden	24	.857	1985	NYM	4	35	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
16	Pedro Martinez P. Martinez	23	.852	1999	BOS	4	31	29	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
17	Lefty Grove L. Grove	28	.848	1930	PHA	5	50	32	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
18	Rick Porcello R. Porcello	22	.846	2016	BOS	4	33	33	3.15	189	3	0	0	223.0	193	78	85	23	32	13	0	0	890	3	7.63	1.29	5.91	0.93	21.2	3.6	1.01	.269	3.43	71	3.39	81	7.79	20.1
19	Mike Hampton M. Hampton	22	.846	1999	HOU	4	34	34	2.90	177	3	2	0	239.0	206	77	86	12	101	5	0	2	979	9	6.67	3.80	1.75	0.45	18.1	10.3	1.28	.284	3.24	68	3.63	84	7.76	19.4
20	Ian Kennedy I. Kennedy	21	.840	2011	ARI	4	33	33	2.88	198	1	1	0	222.0	186	71	73	19	55	9	0	0	900	11	8.03	2.23	3.60	0.77	22.0	6.1	1.09	.270	2.96	73	3.21	83	7.54	16.5
21	Lefty Gomez L. Gomez	26	.839	1934	NYY	5	38	33	2.33	158	25	6	2	281.2	223	73	86	12	96	0	5		1,142	3	5.05	3.07	1.65	0.38	13.8	8.4	1.13	.241	2.75	56	3.57	86	7.13	17.7
22	Denny McLain D. McLain	31	.838	1968	DET	6	41	41	1.96	280	28	6	0	336.0	241	73	86	31	63	6	0	2	1,288	3	7.50	1.69	4.44	0.83	21.7	4.9	0.90	.231	2.30	64	2.53	79	6.46	24.8
23	Bill Hoffer B. Hoffer	31	.838	1895	BAL	6	41	38	3.21	80	32	4	0	314.0	296	112	146	9	124	19	3		1,349	3	2.29	3.55	0.65	0.26	5.9	9.2	1.34	.257	4.18	67	4.81	101	8.48	-1.3
24	Walter Johnson W. Johnson	36	.837	1913	WSH	7	48	36	1.14	243	29	11	2	346.0	232	44	56	9	38	9	10		1,271	2	6.32	0.99	6.39	0.23	19.1	3.0	0.78	.229	1.46	39	1.90	63	6.03	42.3
25	J.A. Happ	20	.833	2016	TOR	4	32	32	3.18	163	0	0	0	195.0	168	69	72	22	60	6	0	0	796	3	7.52	2.77	2.72	1.02	20.5	7.5	1.17	.268	3.32	76	3.95	93	7.75	6.3