most wins in a season by a left handed pitcher

Matt Kilroy has won the most games by a left-hander in a season, with 46 wins in 1887.

	NAME	W	SEASON	TM	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	ERA-	FIP	FIP-	H/9	PRAA
1	Matt Kilroy M. Kilroy	46	1887	BAL	19	.708	69	69	3.07	217	66	6	0	589.1	585	201	326	9	157	20	1		2,492	46	3.31	2.40	1.38	0.14	8.7	6.3	1.26	.276	4.98	73	3.64	90	8.93	23.3
2	Lady Baldwin L. Baldwin	42	1886	DET	13	.764	56	56	2.24	323	55	7	0	487.0	371	121	194	11	100		0		1,936	22	5.97	1.85	3.23	0.20	16.7	5.2	0.97		3.59	68	2.68	81	6.86	33.8
3	Ed Morris E. Morris	41	1886	PIT	20	.672	64	63	2.45	326	63	12	1	555.1	455	151	244	5	118	7	1		2,252	22	5.28	1.91	2.76	0.08	14.5	5.2	1.03	.251	3.95	76	2.72	85	7.37	23.7
4	Ed Morris E. Morris	39	1885	PIT	24	.619	63	63	2.35	298	63	7	0	581.0	459	152	245	5	101	14	0		2,321	36	4.62	1.56	2.95	0.08	12.8	4.4	0.96	.239	3.80	77	2.56	90	7.11	10.9
5	Toad Ramsey T. Ramsey	38	1886	LOU	27	.585	67	67	2.45	499	66	3	0	588.2	447	160	297	3	207	12	0		2,477	35	7.63	3.16	2.41	0.05	20.1	8.4	1.11	.253	4.54	71	2.59	76	6.83	54.7
6	Toad Ramsey T. Ramsey	37	1887	LOU	27	.578	65	64	3.43	355	61	0	0	561.0	544	214	358	9	167	16	1		2,430	46	5.70	2.68	2.13	0.14	14.6	6.9	1.27	.284	5.74	78	3.20	76	8.73	64.2
7	Frank Killen F. Killen	36	1893	PIT	14	.720	55	48	3.64	99	38	2	0	415.0	401	168	235	12	140	15	6		1,784	10	2.15	3.04	0.71	0.26	5.5	7.8	1.30	.256	5.10	80	4.26	93	8.70	12.4
8	Elmer Smith E. Smith	34	1887	CIN	17	.667	52	52	2.94	176	49	3	0	447.1	400	146	224	5	126	9	0		1,872	31	3.54	2.54	1.40	0.10	9.4	6.7	1.18	.254	4.51	68	3.54	85	8.05	31.7
9	Ed Morris E. Morris	34	1884	COL	13	.723	52	52	2.18	302	47	3	0	429.2	335	104	159	3	51	13	0		1,703	22	6.33	1.07	5.92	0.06	17.7	3.0	0.90	.249	3.33	71	2.41	80	7.02	23.3
10	Lee Richmond L. Richmond	32	1880	WOR	32	.500	74	66	2.15	243	57	5	3	590.2	541	141	278	7	74		9		2,410	29	3.70	1.13	3.28	0.11	10.1	3.1	1.04		4.24	85	2.24	88	8.24	28.7
11	Lefty Grove L. Grove	31	1931	PHA	4	.886	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
12	Frank Killen F. Killen	30	1896	PIT	18	.625	52	50	3.41	134	44	5	0	432.1	476	164	244	7	119	14	1		1,850	9	2.79	2.48	1.13	0.15	7.2	6.4	1.38	.298	5.08	82	3.81	91	9.91	15.2
13	Dupee Shaw D. Shaw	30	1884	TOT	33	.476	67	66	2.30	451	60	5	0	543.1	446	139	281	9	109		1		2,244	24	7.47	1.81	4.14	0.15	20.1	4.9	1.02		4.65	77	2.43	81	7.39	29
14	Hal Newhouser H. Newhouser	29	1944	DET	9	.763	47	34	2.22	187	25	6	2	312.1	264	77	94	6	102	1	10		1,271	4	5.39	2.94	1.83	0.17	14.7	8.0	1.17	.265	2.71	62	2.58	72	7.61	34.5
15	Frank Killen F. Killen	29	1892	WSH	26	.527	60	52	3.31	147	46	2	0	459.2	448	169	286	15	182	20	6		2,028	18	2.88	3.56	0.81	0.29	7.2	9.0	1.37	.260	5.60	100	3.54	107	8.77	-10.2
16	Matt Kilroy M. Kilroy	29	1889	BAL	25	.537	59	56	2.85	217	55	5	0	480.2	476	152	283	8	142	27	3		2,070	32	4.06	2.66	1.53	0.15	10.5	6.9	1.29	.279	5.30	76	3.37	90	8.91	18.3
17	Ed Morris E. Morris	29	1888	PIT	23	.558	55	55	2.31	135	54	5	0	480.0	470	123	216	7	74	8	0		2,002	13	2.53	1.39	1.82	0.13	6.7	3.7	1.13	.260	4.05	90	2.72	101	8.81	-12.7
18	Matt Kilroy M. Kilroy	29	1886	BAL	34	.460	68	68	3.37	513	66	5	0	583.0	476	218	350	10	182	19	0		2,469	61	7.92	2.81	2.82	0.15	20.8	7.4	1.13	.267	5.40	100	2.60	77	7.35	47
19	Lefty Grove L. Grove	28	1930	PHA	5	.848	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
20	Phil Knell P. Knell	28	1891	COL	27	.509	58	52	2.92	228	47	5	0	462.0	363	150	228	4	226	54	5		2,017	23	4.44	4.40	1.01	0.08	11.3	11.2	1.27	.239	4.44	84	3.47	103	7.07	-13.4
21	Dan Casey D. Casey	28	1887	PHN	13	.683	45	45	2.86	119	43	4	0	390.1	377	124	199	15	115	14	0		1,660	16	2.74	2.65	1.03	0.35	7.2	6.9	1.26	.259	4.59	69	4.16	96	8.69	8.7
22	Steve Carlton S. Carlton	27	1972	PHI	10	.730	41	41	1.97	310	30	8	0	346.1	257	76	84	17	87	1	0	8	1,351	8	8.06	2.26	3.56	0.44	22.9	6.4	0.99	.256	2.18	56	2.00	59	6.68	53.5
23	Sandy Koufax S. Koufax	27	1966	LAD	9	.750	41	41	1.73	317	27	5	0	323.0	241	62	74	19	77	0	0	4	1,274	7	8.83	2.15	4.12	0.53	24.9	6.0	0.98	.258	2.06	53	2.07	65	6.72	41.8
24	Doc White D. White	27	1907	CWS	13	.675	46	35	2.26	141	24	6	1	291.0	270	73	93	3	38	6	9		1,131	0	4.36	1.18	3.71	0.09	12.5	3.4	1.06	.283	2.88	95	1.80	80	8.35	12.8
25	Rube Waddell R. Waddell	27	1905	PHA	10	.730	46	34	1.48	287	27	7	0	328.2	231	54	86	5	90	10	11		1,257	10	7.86	2.46	3.19	0.14	22.8	7.2	0.98	.261	2.35	55	1.89	69	6.33	31.2