Bucky Walters had the lowest ERA in 1939, with an ERA of 2.29.

Interpreted as:

lowest era with a minimum of 1 IP per team game by a player in 1939

	NAME	ERA	SEASON	TM	G	W	L	W%	GS	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	Bucky Walters B. Walters	2.29	1939	CIN	39	27	11	.711	36	137	31	2	0	319.0	250	81	98	15	109	6	2	1,283	8	3.87	3.08	1.26	0.42	10.7	8.5	1.13	.231	2.76	60	3.81	96	7.05	4.8
2	Lefty Grove L. Grove	2.54	1939	BSA	23	15	4	.789	23	81	17	2	0	191.0	180	54	63	8	58	1	0	798	0	3.82	2.73	1.40	0.38	10.2	7.3	1.25	.265	2.97	53	3.60	78	8.48	20.9
3	Bob Bowman B. Bowman	2.60	1939	SLN	51	13	5	.722	15	78	4	2	8	169.1	141	49	54	8	60	1	19	692	3	4.15	3.19	1.30	0.43	11.3	8.7	1.19	.244	2.87	63	3.75	87	7.49	10.2
4	Carl Hubbell C. Hubbell	2.75	1939	NYG	29	11	9	.550	18	62	10	0	2	154.0	150	47	60	11	24	2	8	639	2	3.62	1.40	2.58	0.64	9.7	3.8	1.13	.257	3.51	69	3.60	87	8.77	8.9
5	Ted Lyons T. Lyons	2.76	1939	CWS	21	14	6	.700	21	65	16	0	0	172.2	162	53	71	7	26	1	0	702	0	3.39	1.36	2.50	0.36	9.3	3.7	1.09	.257	3.70	60	3.22	73	8.44	23
6	Bob Feller B. Feller	2.85	1939	CLE	39	24	9	.727	35	246	24	4	1	296.2	227	94	105	13	142	3	3	1,243	14	7.46	4.31	1.73	0.39	19.8	11.4	1.24	.255	3.19	64	3.35	78	6.89	32.4
7	Hugh Casey H. Casey	2.93	1939	BKN	40	15	10	.600	25	79	15	0	1	227.1	228	74	88	13	54	11	11	962	4	3.13	2.14	1.46	0.51	8.2	5.6	1.24	.267	3.48	73	3.88	92	9.03	8.4
8	Paul Derringer P. Derringer	2.93	1939	CIN	38	25	7	.781	35	128	28	5	0	301.0	321	98	115	15	35	3	1	1,245	2	3.83	1.05	3.66	0.45	10.3	2.8	1.18	.288	3.44	77	3.15	80	9.60	27.2
9	Red Ruffing R. Ruffing	2.93	1939	NYY	28	21	7	.750	28	95	22	5	0	233.1	211	76	88	15	75	2	0	968	3	3.66	2.89	1.27	0.58	9.8	7.7	1.23	.251	3.39	66	3.98	93	8.14	7.2
10	Bump Hadley B. Hadley	2.98	1939	NYY	26	12	6	.667	18	65	7	1	2	154.0	132	51	62	10	85	3	6	658	4	3.80	4.97	0.76	0.58	9.9	12.9	1.41	.246	3.62	67	4.69	110	7.71	-7.7
11	Milt Shoffner M. Shoffner	3.18	1939	TOT	35	6	8	.429	14	57	7	0	1	170.0	176	60	74	7	53	3	12	729	1	3.02	2.81	1.08	0.37	7.8	7.3	1.35	.278	3.92	86	3.83	100	9.32	-0.6
12	Mort Cooper M. Cooper	3.25	1939	SLN	45	12	6	.667	26	130	7	2	5	210.2	208	76	94	6	97	2	12	919	4	5.55	4.14	1.34	0.26	14.1	10.6	1.45	.295	4.02	79	3.52	82	8.89	17.7
13	Claude Passeau C. Passeau	3.28	1939	TOT	42	15	13	.536	35	137	17	2	3	274.1	269	100	112	9	73	5	6	1,150	0	4.49	2.39	1.88	0.30	11.9	6.3	1.25	.281	3.67	84	3.25	80	8.83	25.2
14	Larry French L. French	3.29	1939	CHC	36	15	8	.652	21	98	10	2	1	194.0	205	71	80	7	50	1	11	828	5	4.55	2.32	1.96	0.32	11.8	6.0	1.31	.295	3.71	84	3.22	79	9.51	18.5
15	Mace Brown M. Brown	3.37	1939	PIT	47	9	13	.409	19	71	8	1	7	200.1	232	75	90	8	52	2	18	872	3	3.19	2.34	1.37	0.36	8.1	6.0	1.42	.303	4.04	86	3.59	88	10.42	10.8
16	Lefty Gomez L. Gomez	3.41	1939	NYY	26	12	8	.600	26	102	14	2	0	198.0	173	75	80	11	84	3	0	831	3	4.64	3.82	1.21	0.50	12.3	10.1	1.30	.257	3.64	77	3.98	93	7.86	6.2
17	Bill Lee B. Lee	3.44	1939	CHC	37	19	15	.559	36	105	20	1	0	282.1	295	108	125	18	85	1	1	1,202	4	3.35	2.71	1.24	0.57	8.7	7.1	1.35	.279	3.98	88	3.97	97	9.40	3.4
18	Whitey Moore W. Moore	3.45	1939	CIN	42	13	12	.520	24	81	9	2	3	187.2	177	72	88	10	95	6	11	819	3	3.88	4.56	0.85	0.48	9.9	11.6	1.45	.266	4.22	91	4.42	112	8.49	-10.3
19	Tommy Bridges T. Bridges	3.50	1939	DET	29	17	7	.708	26	129	16	2	2	198.0	186	77	87	11	61	6	2	840	4	5.86	2.77	2.11	0.50	15.4	7.3	1.25	.276	3.95	71	3.41	72	8.45	28.1
20	Mel Harder M. Harder	3.50	1939	CLE	29	15	9	.625	26	67	12	1	1	208.0	213	81	89	15	64	3	3	877	1	2.90	2.77	1.05	0.65	7.6	7.3	1.33	.272	3.85	78	4.23	98	9.22	1.7
21	Dutch Leonard D. Leonard	3.54	1939	WSH	34	20	8	.714	34	88	21	2	0	269.1	273	106	124	16	59	5	0	1,133	6	2.94	1.97	1.49	0.53	7.8	5.2	1.23	.266	4.14	81	3.80	90	9.12	12.5
22	Cliff Melton C. Melton	3.56	1939	NYG	41	12	15	.444	23	95	9	2	5	207.1	214	82	94	7	65	4	13	886	2	4.12	2.82	1.46	0.30	10.7	7.3	1.35	.290	4.08	90	3.49	85	9.29	14.4
23	Bobo Newsom B. Newsom	3.58	1939	TOT	41	20	11	.645	37	192	24	3	2	291.2	272	116	126	19	126	3	4	1,261	4	5.92	3.89	1.52	0.59	15.2	10.0	1.36	.275	3.89	73	3.83	81	8.39	28
24	Dizzy Trout D. Trout	3.61	1939	DET	33	9	10	.474	22	72	6	0	2	162.0	168	65	82	5	74	4	6	716	5	4.00	4.11	0.97	0.28	10.1	10.3	1.49	.291	4.56	74	3.93	83	9.33	14.1
25	Curt Davis C. Davis	3.63	1939	SLN	49	22	16	.579	31	70	13	3	7	248.0	279	100	121	18	48	3	14	1,059	2	2.54	1.74	1.46	0.65	6.6	4.5	1.32	.284	4.39	88	3.97	93	10.13	9.1