most losses in a season by a pitcher in the last 50 years

Between October 29, 1975 and October 29, 2025, Mike Maroth has lost the most games in a season, with 21 games in 2003.

	NAME	L	SEASON	TM	W	L%	G	W%	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	H/9
1	Mike Maroth M. Maroth	21	2003	DET	9	.700	33	.300	33	5.73	87	1	0	0	193.1	231	123	131	34	50	8	0	2	847	7	4.05	2.33	1.74	1.58	10.3	5.9	1.45	.295	6.10	10.75
2	Brian Kingman B. Kingman	20	1980	OAK	8	.714	32	.286	30	3.83	116	10	1	0	211.1	209	90	105	21	82	4	0	5	912	6	4.94	3.49	1.41	0.89	12.7	9.0	1.38	.273	4.47	8.90
3	Phil Niekro P. Niekro	20	1979	ATL	21	.488	44	.512	44	3.39	208	23	1	0	342.0	311	129	160	41	113	11	0	8	1,436	18	5.47	2.97	1.84	1.08	14.5	7.9	1.24	.254	4.21	8.18
4	Jerry Koosman J. Koosman	20	1977	NYM	8	.714	32	.286	32	3.49	192	6	1	0	226.2	195	88	102	17	81	4	0	8	940	2	7.62	3.22	2.37	0.68	20.4	8.6	1.22	.276	4.05	7.74
5	Phil Niekro P. Niekro	20	1977	ATL	16	.556	44	.444	43	4.03	262	20	2	0	330.1	315	148	166	26	164	8	1	12	1,428	17	7.14	4.47	1.60	0.71	18.3	11.5	1.45	.299	4.52	8.58
6	Patrick Corbin P. Corbin	19	2022	WSH	6	.760	31	.240	31	6.31	128	1	0	0	152.2	210	107	119	27	49	7	0	1	713	2	7.55	2.89	2.61	1.59	18.0	6.9	1.70	.365	7.02	12.38
7	James Shields J. Shields	19	2016	TOT	6	.760	33	.240	33	5.85	135	1	0	0	181.2	208	118	122	40	82	8	0	3	822	10	6.69	4.06	1.65	1.98	16.4	10.0	1.60	.302	6.04	10.30
8	Chris Archer C. Archer	19	2016	TBR	9	.679	33	.321	33	4.02	233	0	0	0	201.1	183	90	100	30	67	3	0	0	850	11	10.42	3.00	3.48	1.34	27.4	7.9	1.24	.296	4.47	8.18
9	Darrell May D. May	19	2004	KCR	9	.679	31	.321	31	5.61	120	3	1	0	186.0	234	116	130	38	55	2	0	4	832	2	5.81	2.66	2.18	1.84	14.4	6.6	1.55	.318	6.29	11.32
10	Jeremy Bonderman J. Bonderman	19	2003	DET	6	.760	33	.240	28	5.56	108	0	0	0	162.0	193	100	118	23	58	4	0	2	727	12	6.00	3.22	1.86	1.28	14.9	8.0	1.55	.318	6.56	10.72
11	Bobby Jones B. Jones	19	2001	SDP	8	.704	33	.296	33	5.12	113	1	0	0	195.0	250	111	137	37	38	4	0	6	880	3	5.22	1.75	2.97	1.71	12.8	4.3	1.48	.310	6.32	11.54
12	Albie Lopez A. Lopez	19	2001	TOT	9	.679	33	.321	33	4.81	136	3	3	0	205.2	226	110	123	26	75	4	0	3	896	2	5.95	3.28	1.81	1.14	15.2	8.4	1.46	.305	5.38	9.89
13	Omar Daal O. Daal	19	2000	TOT	4	.826	32	.174	28	6.14	96	0	0	0	167.0	208	114	128	26	72	9	1	11	775	0	5.17	3.88	1.33	1.40	12.4	9.3	1.68	.318	6.90	11.21
14	Scott Erickson S. Erickson	19	1993	MIN	8	.704	34	.296	34	5.19	116	1	0	0	218.2	266	126	138	17	71	10	0	1	976	5	4.77	2.92	1.63	0.70	11.9	7.3	1.54	.327	5.68	10.95
15	Kirk McCaskill K. McCaskill	19	1991	CAL	10	.655	30	.345	30	4.26	71	1	0	0	177.2	193	84	93	19	66	3	0	1	762	6	3.60	3.34	1.08	0.96	9.3	8.7	1.46	.289	4.71	9.78
16	Tim Leary T. Leary	19	1990	NYY	9	.679	31	.321	31	4.11	138	6	1	0	208.0	202	95	105	18	78	7	0	1	881	23	5.97	3.38	1.77	0.78	15.7	8.9	1.35	.288	4.54	8.74
17	Jose DeLeon J. DeLeon	19	1990	STL	7	.731	32	.269	32	4.43	164	0	0	0	182.2	168	90	96	15	86	5	0	9	793	5	8.08	4.24	1.91	0.74	20.7	10.8	1.39	.293	4.73	8.28
18	Mike Moore M. Moore	19	1987	SEA	9	.679	33	.321	33	4.71	115	12	0	0	231.0	268	121	145	29	84	0	0	3	1,020	4	4.48	3.27	1.37	1.13	11.3	8.2	1.52	.302	5.65	10.44
19	Matt Young M. Young	19	1985	SEA	12	.613	37	.387	35	4.91	136	5	2	1	218.1	242	119	135	23	76	7	2	3	951	6	5.61	3.13	1.79	0.95	14.3	8.0	1.46	.309	5.56	9.98
20	Jose DeLeon J. DeLeon	19	1985	PIT	2	.905	31	.095	25	4.70	149	1	0	3	162.2	138	85	93	15	89	3	5	3	700	7	8.24	4.92	1.67	0.83	21.3	12.7	1.40	.277	5.15	7.64
21	Rick Wise R. Wise	19	1978	CLE	9	.679	33	.321	31	4.34	106	9	1	0	211.2	226	102	116	22	59	3	1	3	903	1	4.51	2.51	1.80	0.94	11.7	6.5	1.35	.286	4.93	9.61
22	Vida Blue V. Blue	19	1977	OAK	14	.576	38	.424	38	3.83	157	16	1	0	279.2	284	119	138	23	86	1	0	5	1,184	11	5.05	2.77	1.83	0.74	13.3	7.3	1.32	.285	4.44	9.14
23	Wayne Garland W. Garland	19	1977	CLE	13	.594	38	.406	38	3.60	118	21	1	0	282.2	281	113	130	23	88	2	0	8	1,184	12	3.76	2.80	1.34	0.73	10.0	7.4	1.31	.271	4.14	8.95
24	Rick Langford R. Langford	19	1977	OAK	8	.704	37	.296	31	4.02	141	6	1	0	208.1	223	93	107	18	73	2	2	3	901	4	6.09	3.15	1.93	0.78	15.6	8.1	1.42	.307	4.62	9.63
25	A.J. Burnett	18	2014	PHI	8	.692	34	.308	34	4.59	190	1	0	0	213.2	205	109	122	20	96	16	0	2	935	9	8.00	4.04	1.98	0.84	20.3	10.3	1.41	.302	5.14	8.63