George Caster and Hugh Mulcahy were tied for losing the most games in 1938, with 20 games.

Interpreted as:

most losses by a player in 1938

	NAME	L	SEASON	TM	W	L%	G	W%	GS	ERA	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	ERA-	FIP	FIP-	H/9	PRAA
1	George Caster G. Caster	20	1938	PHA	16	.556	42	.444	40	4.35	112	20	2	1	281.1	310	136	156	25	117	3	2	1,250	5	3.58	3.74	0.96	0.80	9.0	9.4	1.52	.287	4.99	90	4.56	98	9.92	2.7
2	Hugh Mulcahy H. Mulcahy	20	1938	PHN	10	.667	46	.333	34	4.61	90	15	0	1	267.1	294	137	162	14	120	6	8	1,201	5	3.03	4.04	0.75	0.47	7.5	10.0	1.55	.288	5.45	122	4.35	109	9.90	-11.1
3	Larry French L. French	19	1938	CHC	10	.655	43	.345	27	3.80	83	10	3	0	201.1	210	85	95	17	62	1	11	853	4	3.71	2.77	1.34	0.76	9.7	7.3	1.35	.280	4.25	99	4.14	103	9.39	-2.6
4	Al Hollingsworth A. Hollingsworth	18	1938	TOT	7	.720	33	.280	25	4.36	93	12	1	0	208.1	220	101	117	6	89	0	4	912	8	4.02	3.84	1.04	0.26	10.2	9.8	1.48	.296	5.05	116	3.69	93	9.50	6
5	Claude Passeau C. Passeau	18	1938	PHN	11	.621	44	.379	33	4.52	100	15	0	1	239.0	281	120	147	8	93	8	7	1,096	4	3.77	3.50	1.08	0.30	9.1	8.5	1.56	.308	5.54	119	3.79	95	10.58	4.8
6	Jim Turner J. Turner	18	1938	BSN	14	.563	35	.438	34	3.46	71	22	3	0	268.0	267	103	123	21	54	5	1	1,107	1	2.38	1.81	1.31	0.71	6.4	4.9	1.20	.257	4.13	98	4.07	110	8.97	-13.7
7	Bobo Newsom B. Newsom	16	1938	SLA	20	.444	44	.556	40	5.08	226	31	0	1	329.2	334	186	205	30	192	5	3	1,475	3	6.17	5.24	1.18	0.82	15.3	13.0	1.60	.297	5.60	101	4.53	94	9.12	11.6
8	Buck Ross B. Ross	16	1938	PHA	9	.640	29	.360	28	5.32	54	10	0	0	184.1	218	109	132	23	80	0	1	849	1	2.64	3.91	0.68	1.12	6.4	9.4	1.62	.282	6.44	110	5.26	113	10.64	-12.4
9	Luke Hamlin L. Hamlin	15	1938	BKN	12	.556	44	.444	30	3.68	97	10	3	6	237.1	243	97	111	14	65	2	9	997	2	3.68	2.46	1.49	0.53	9.7	6.5	1.30	.280	4.21	94	3.72	91	9.21	10
10	Dutch Leonard D. Leonard	15	1938	WSH	12	.556	33	.444	31	3.43	68	15	3	0	223.1	221	85	109	11	53	7	1	939	11	2.74	2.14	1.28	0.44	7.2	5.6	1.23	.263	4.39	75	3.76	86	8.91	14.9
11	Jack Wilson J. Wilson	15	1938	BSA	15	.500	37	.500	27	4.30	96	11	3	1	194.2	200	93	108	16	91	2	7	869	2	4.44	4.21	1.05	0.74	11.0	10.5	1.49	.277	4.99	87	4.44	94	9.25	6.7
12	Russ Bauers R. Bauers	14	1938	PIT	13	.519	40	.481	34	3.07	117	12	2	3	243.0	207	83	102	7	99	6	6	1,008	6	4.33	3.67	1.18	0.26	11.6	9.8	1.26	.257	3.78	82	3.63	92	7.67	8
13	Paul Derringer P. Derringer	14	1938	CIN	21	.400	41	.600	37	2.93	132	26	4	3	307.0	315	100	110	20	49	0	4	1,263	1	3.87	1.44	2.69	0.59	10.5	3.9	1.19	.278	3.22	80	3.39	88	9.23	15.5
14	Cliff Melton C. Melton	14	1938	NYG	14	.500	36	.500	31	3.89	101	10	1	0	243.0	266	105	126	19	61	1	3	1,042	0	3.74	2.26	1.66	0.70	9.7	5.9	1.35	.287	4.67	103	3.87	98	9.85	2.6
15	Tot Pressnell T. Pressnell	14	1938	BKN	11	.560	43	.440	19	3.56	57	6	1	4	192.0	209	76	86	11	56	8	19	836	5	2.67	2.63	1.02	0.52	6.8	6.7	1.38	.281	4.03	91	4.08	100	9.80	0.8
16	Bud Thomas B. Thomas	14	1938	PHA	9	.609	42	.391	29	4.92	48	7	1	0	212.1	259	116	138	23	62	2	9	945	5	2.03	2.63	0.77	0.97	5.1	6.6	1.51	.291	5.85	102	4.78	103	10.98	-3.1
17	Bucky Walters B. Walters	14	1938	TOT	15	.483	39	.517	34	4.20	93	20	3	1	251.0	259	117	134	13	108	5	3	1,111	11	3.33	3.87	0.86	0.47	8.4	9.7	1.46	.276	4.80	113	4.21	108	9.29	-9.1
18	Lou Fette L. Fette	13	1938	BSN	11	.542	33	.458	32	3.15	83	17	3	1	239.2	235	84	95	11	79	4	1	1,011	1	3.12	2.97	1.05	0.41	8.2	7.8	1.31	.269	3.57	90	3.87	105	8.82	-6.3
19	Harry Gumbert H. Gumbert	13	1938	NYG	15	.464	38	.536	33	4.01	84	14	1	0	235.2	238	105	114	13	84	7	1	1,015	2	3.21	3.21	1.00	0.50	8.3	8.3	1.37	.272	4.35	106	4.09	103	9.09	-3
20	Max Butcher M. Butcher	12	1938	TOT	9	.571	36	.429	20	4.47	50	14	0	2	171.0	198	85	106	15	70	3	8	769	5	2.63	3.68	0.71	0.79	6.5	9.1	1.57	.290	5.58	116	4.76	118	10.42	-13.5
21	Peaches Davis P. Davis	12	1938	CIN	7	.632	29	.368	19	3.97	28	11	1	1	167.2	193	74	86	9	40	1	4	719	1	1.50	2.15	0.70	0.48	3.9	5.6	1.39	.287	4.62	108	4.02	104	10.36	-3.6
22	Lefty Gomez L. Gomez	12	1938	NYY	18	.400	32	.600	32	3.35	129	20	4	0	239.0	239	89	110	7	99	1	0	1,034	5	4.86	3.73	1.30	0.26	12.5	9.6	1.41	.291	4.14	73	3.48	79	9.00	25.1
23	Jack Knott J. Knott	12	1938	TOT	6	.667	27	.333	22	4.19	43	9	0	0	161.0	170	75	89	11	69	0	3	705	0	2.40	3.86	0.62	0.61	6.1	9.8	1.48	.273	4.98	87	4.56	98	9.50	1.5
24	Thornton Lee T. Lee	12	1938	CWS	13	.480	33	.520	30	3.49	77	18	1	1	245.1	252	95	123	12	94	3	3	1,074	2	2.82	3.45	0.82	0.44	7.2	8.8	1.41	.270	4.51	73	4.12	90	9.24	13.1
25	Bill McGee B. McGee	12	1938	SLN	7	.632	47	.368	25	3.21	104	10	1	5	216.0	216	77	101	4	78	1	11	932	2	4.33	3.25	1.33	0.17	11.2	8.4	1.36	.285	4.21	83	3.30	81	9.00	18