Between the 1980 and 1989 seasons, Jim Clancy lost the most games, with 126 games.

Interpreted as:

most regular-season losses by a pitcher in the 1980s

	NAME	L	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	ERA-	FIP	FIP-	H/9	PRAA
1	Jim Clancy J. Clancy	126	119	.514	329	.486	317	4.09	1,145	61	10	1	2017.2	1,996	918	1,017	207	711	27	8	30	8,582	72	5.11	3.17	1.61	0.92	13.3	8.3	1.34	.276	4.54	100	4.04	100	8.90	1.9
2	Frank Tanana F. Tanana	122	107	.533	314	.467	304	3.89	1,225	51	8	0	1994.0	2,014	861	989	219	589	55	3	59	8,493	55	5.53	2.66	2.08	0.99	14.4	6.9	1.31	.280	4.46	97	3.91	97	9.09	27
3	Jack Morris J. Morris	119	162	.423	332	.577	332	3.66	1,629	133	20	0	2443.2	2,212	995	1,085	264	858	23	0	66	10,208	124	6.00	3.16	1.90	0.97	16.0	8.4	1.26	.262	4.00	92	3.89	94	8.15	66.7
4	Bob Knepper B. Knepper	118	105	.529	332	.471	306	3.70	1,068	50	20	1	2005.1	2,045	824	946	167	597	36	8	52	8,484	39	4.79	2.68	1.79	0.75	12.6	7.0	1.32	.284	4.25	107	3.70	107	9.18	-64.6
5	Charlie Hough C. Hough	114	128	.471	331	.529	282	3.67	1,363	93	11	2	2121.2	1,842	864	999	218	867	80	22	18	8,942	98	5.78	3.68	1.57	0.92	15.2	9.7	1.28	.253	4.24	90	4.14	103	7.81	-28.2
6	Floyd Bannister F. Bannister	109	112	.493	297	.507	294	3.98	1,356	50	11	0	1890.2	1,813	836	929	234	616	28	0	23	7,994	66	6.45	2.93	2.20	1.11	17.0	7.7	1.28	.274	4.42	96	3.94	96	8.63	35.4
7	Richard Dotson R. Dotson	109	109	.500	292	.500	283	4.16	951	54	10	0	1804.1	1,813	835	922	191	720	40	6	23	7,788	42	4.74	3.59	1.32	0.95	12.2	9.2	1.40	.276	4.60	102	4.33	108	9.04	-62.1
8	Dave Stieb D. Stieb	109	140	.438	339	.562	331	3.32	1,380	92	27	1	2328.2	2,019	859	954	183	825	104	4	29	9,654	39	5.33	3.19	1.67	0.71	14.3	8.5	1.22	.256	3.69	80	3.77	93	7.80	77.5
9	Mike Moore M. Moore	107	85	.557	262	.443	252	4.13	1,109	62	12	2	1698.2	1,691	779	865	160	618	31	6	32	7,219	59	5.88	3.27	1.79	0.85	15.4	8.6	1.36	.289	4.58	99	3.82	90	8.96	74.3
10	Mike Witt M. Witt	104	109	.488	304	.512	272	3.78	1,269	70	10	5	1945.0	1,913	816	917	166	643	47	18	36	8,220	64	5.87	2.98	1.97	0.77	15.4	7.8	1.31	.287	4.24	95	3.61	88	8.85	109.1
11	Nolan Ryan N. Ryan	104	122	.460	314	.540	314	3.14	2,167	44	15	0	2094.0	1,603	730	835	128	894	53	0	34	8,704	123	9.31	3.84	2.42	0.55	24.9	10.3	1.19	.270	3.59	90	2.82	81	6.89	159.5
12	Bert Blyleven B. Blyleven	103	123	.456	291	.544	288	3.64	1,480	94	21	0	2078.1	1,984	841	919	212	557	73	1	26	8,623	44	6.41	2.41	2.66	0.92	17.2	6.5	1.22	.281	3.98	89	3.56	88	8.59	109.6
13	Fernando Valenzuela F. Valenzuela	103	128	.446	298	.554	287	3.19	1,644	102	27	2	2144.2	1,876	760	869	133	838	16	5	54	8,957	81	6.90	3.52	1.96	0.56	18.4	9.4	1.27	.276	3.65	91	3.21	90	7.87	84
14	Danny Darwin D. Darwin	101	95	.515	417	.485	184	3.48	1,090	43	8	27	1663.1	1,579	643	738	145	519	38	127	60	6,995	30	5.90	2.81	2.10	0.78	15.6	7.4	1.26	.276	3.99	91	3.57	94	8.54	40.7
15	Rick Honeycutt R. Honeycutt	101	79	.561	359	.439	213	3.62	700	35	9	20	1501.0	1,529	603	703	122	431	28	49	49	6,314	30	4.20	2.58	1.62	0.73	11.1	6.8	1.31	.280	4.22	96	3.78	99	9.17	2.5
16	Rick Mahler R. Mahler	101	87	.537	319	.463	247	3.93	845	41	8	2	1728.2	1,837	754	852	141	528	30	16	63	7,350	36	4.40	2.75	1.60	0.73	11.5	7.2	1.37	.292	4.44	102	3.79	99	9.56	7.5
17	Shane Rawley S. Rawley	100	102	.495	369	.505	225	4.02	877	41	7	25	1675.2	1,732	749	820	144	643	22	87	56	7,215	45	4.71	3.45	1.36	0.77	12.2	8.9	1.42	.287	4.40	104	4.01	105	9.30	-31.7
18	Rick Rhoden R. Rhoden	100	109	.478	294	.522	288	3.65	1,092	48	10	1	1918.1	1,954	779	856	139	596	32	4	57	8,082	63	5.12	2.80	1.83	0.65	13.5	7.4	1.33	.292	4.02	98	3.52	94	9.17	46.3
19	Frank Viola F. Viola	98	117	.456	272	.544	271	3.84	1,287	56	11	0	1858.0	1,850	792	877	218	548	30	0	20	7,801	48	6.23	2.65	2.35	1.06	16.5	7.0	1.29	.285	4.25	91	3.83	94	8.96	46.2
20	Doyle Alexander D. Alexander	98	112	.467	300	.533	289	3.85	1,029	51	10	0	2004.1	2,065	858	930	223	503	32	7	28	8,423	34	4.62	2.26	2.05	1.00	12.2	6.0	1.28	.278	4.18	97	3.96	100	9.27	3.7
21	Joe Niekro J. Niekro	96	105	.478	264	.522	259	3.56	884	52	12	0	1713.2	1,624	677	783	119	623	32	3	26	7,247	110	4.64	3.27	1.42	0.62	12.2	8.6	1.31	.269	4.11	99	3.75	105	8.53	-42
22	Mike Flanagan M. Flanagan	94	103	.477	278	.523	276	4.01	845	49	10	0	1740.0	1,801	776	846	170	568	25	1	25	7,400	57	4.37	2.94	1.49	0.88	11.4	7.7	1.36	.282	4.38	101	4.06	101	9.32	-6.1
23	Rick Sutcliffe R. Sutcliffe	93	116	.445	310	.555	260	3.87	1,285	59	15	6	1860.0	1,764	799	866	160	745	28	27	56	7,887	74	6.22	3.60	1.72	0.77	16.3	9.4	1.35	.283	4.19	99	3.74	96	8.54	34.8
24	Bob Welch B. Welch	93	137	.404	313	.596	311	3.21	1,457	47	22	0	2082.1	1,885	743	821	155	666	49	0	40	8,655	43	6.30	2.88	2.19	0.67	16.8	7.7	1.23	.273	3.55	90	3.34	92	8.15	63.4
25	Mike Krukow M. Krukow	91	98	.481	278	.519	274	3.81	1,171	37	8	1	1711.1	1,690	724	823	156	570	36	1	60	7,302	59	6.16	3.00	2.05	0.82	16.0	7.8	1.32	.286	4.33	105	3.62	99	8.89	8.6