The Seattle Mariners had their worst record in a season in 1978, with a record of 56-104.

	TEAM	REC	SEASON	W%	G	W	L	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Mariners	56-104	1978	.350	160	56	104	5,358	614	1,327	229	37	97	571	522	22	702	123	47	6,023	1,921	363	68	53	25	112	.248	.314	.359	.673
2	Mariners	59-103	1980	.364	163	59	103	5,489	610	1,359	211	35	104	564	483	19	727	116	62	6,141	1,952	350	106	44	44	136	.248	.308	.356	.664
3	Mariners	60-102	1983	.370	162	60	102	5,336	558	1,280	247	31	111	536	460	24	840	144	80	5,905	1,922	389	40	45	31	113	.240	.301	.360	.661
4	Mariners	61-101	2010	.377	162	61	101	5,409	513	1,274	227	16	101	485	459	39	1,184	142	39	5,989	1,836	344	42	40	33	110	.236	.298	.339	.637
5	Mariners	61-101	2008	.377	162	61	101	5,643	671	1,498	285	20	124	631	417	38	890	90	32	6,176	2,195	429	36	42	44	137	.265	.318	.389	.707
6	Mariners	63-99	2004	.389	162	63	99	5,722	698	1,544	276	20	136	658	492	54	1,058	110	42	6,362	2,268	432	46	48	49	131	.270	.331	.396	.727
7	Mariners	64-98	1992	.395	162	64	98	5,564	679	1,466	278	24	149	638	474	38	841	100	55	6,179	2,239	451	52	51	47	148	.263	.323	.402	.725
8	Mariners	64-98	1977	.395	162	64	98	5,460	624	1,398	218	33	133	589	426	35	769	110	67	6,044	2,081	384	81	42	22	114	.256	.312	.381	.693
9	Mariners	44-65	1981	.404	110	44	65	3,780	426	950	148	13	89	406	329	27	553	100	50	4,201	1,391	250	41	24	24	70	.251	.314	.368	.682
10	Mariners	67-95	2011	.414	162	67	95	5,421	556	1,263	253	22	109	534	435	37	1,280	125	40	5,972	1,887	384	38	41	33	82	.233	.292	.348	.640
11	Mariners	67-95	1986	.414	162	67	95	5,498	718	1,392	243	41	158	681	572	34	1,148	93	76	6,185	2,191	442	52	29	38	125	.253	.326	.399	.724
12	Mariners	67-95	1979	.414	162	67	95	5,544	711	1,490	250	52	132	676	515	28	725	126	52	6,202	2,240	434	61	54	45	158	.269	.331	.404	.735
13	Mariners	68-94	2019	.420	162	68	94	5,500	758	1,305	254	28	239	730	588	58	1,581	115	47	6,197	2,332	521	14	37	7	83	.237	.316	.424	.740
14	Mariners	68-93	1988	.422	161	68	93	5,436	664	1,397	271	27	148	617	461	38	787	95	61	6,017	2,166	446	40	42	24	135	.257	.317	.398	.716
15	Mariners	69-93	2005	.426	162	69	93	5,507	699	1,408	289	34	130	657	466	48	986	102	47	6,095	2,155	453	37	37	50	115	.256	.317	.391	.709
16	Mariners	49-63	1994	.438	112	49	63	3,883	569	1,045	211	18	153	549	372	26	652	48	21	4,361	1,751	382	48	32	42	87	.269	.335	.451	.786
17	Mariners	71-91	2013	.438	162	71	91	5,558	624	1,318	249	17	188	597	529	31	1,353	49	23	6,172	2,165	454	26	28	21	122	.237	.306	.390	.695
18	Mariners	27-33	2020	.450	60	27	33	1,929	254	435	88	5	60	244	207	30	545	50	16	2,181	713	153	3	12	5	35	.226	.309	.370	.678
19	Mariners	73-89	1989	.451	162	73	89	5,512	694	1,417	237	29	134	653	489	45	838	81	55	6,133	2,114	400	35	52	40	109	.257	.320	.384	.703
20	Mariners	74-88	1985	.457	162	74	88	5,521	719	1,410	277	38	171	686	564	31	942	94	35	6,185	2,276	486	28	41	36	147	.255	.326	.412	.738
21	Mariners	74-88	1984	.457	162	74	88	5,546	682	1,429	244	34	129	635	519	42	871	116	62	6,211	2,128	407	66	38	35	101	.258	.324	.384	.708
22	Mariners	75-87	2012	.463	162	75	87	5,494	619	1,285	241	27	149	584	466	30	1,259	104	35	6,057	2,027	417	32	35	21	95	.234	.296	.369	.665
23	Mariners	76-86	2015	.469	162	76	86	5,544	656	1,379	262	22	198	624	478	36	1,336	69	45	6,131	2,279	482	38	35	31	123	.249	.311	.411	.722
24	Mariners	76-86	1982	.469	162	76	86	5,626	651	1,431	259	33	130	614	456	22	806	131	82	6,181	2,146	422	42	35	31	113	.254	.311	.381	.692
25	Mariners	76-85	1998	.472	161	76	85	5,628	859	1,553	321	28	234	822	558	57	1,081	115	39	6,327	2,632	583	36	48	26	107	.276	.345	.468	.812