worst era by a team in a month with 10 games played from 1901 to 2023

Between the 1901 and 2023 seasons, the St. Louis Browns had the highest ERA by a team when pitching in 10+ games in a month, with an ERA of 8.04 in April 1951.

Interpreted as:

worst era by a team in a month with 10 or more games played from 1901 to 2023

	TEAM	ERA	G	MONTH	W%	W	L	SO	SHO	SV	IP	H	ER	R	HR	BB	HBP	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	H/9
1	Browns	8.04	12	April 1951	.333	4	8	46	0	1	103.0	128	92	94	14	87	6		517	1	4.02	7.60	0.53	1.22	8.9	16.8	2.09	.313	8.21	11.18
2	Athletics	7.97	28	April 2023	.179	5	23	206	0	2	245.0	300	217	229	50	141	24	4	1,176	18	7.57	5.18	1.46	1.84	17.5	12.0	1.80	.331	8.41	11.02
3	Athletics	7.56	14	April 1955	.429	6	8	56	2	1	125.0	148	105	115	25	91	9	9	603	5	4.03	6.55	0.62	1.80	9.3	15.1	1.91	.291	8.28	10.66
4	Orioles	7.39	28	August 2021	.143	4	24	194	0	1	241.0	277	198	208	53	105	12	2	1,102	17	7.24	3.92	1.85	1.98	17.6	9.5	1.59	.304	7.77	10.34
5	Twins	7.34	25	April 1994	.360	9	16	125	1	6	220.2	312	180	198	49	102	9	7	1,056	11	5.10	4.16	1.23	2.00	11.8	9.7	1.88	.341	8.08	12.73
6	Pirates	7.33	26	June 1950	.280	7	18	89	1	3	229.2	293	187	209	42	121	4		1,084	11	3.49	4.74	0.74	1.65	8.2	11.2	1.80	.303	8.19	11.48
7	Tigers	7.31	27	April 1996	.333	9	18	174	0	2	237.2	288	193	211	50	138	14	10	1,137	15	6.59	5.23	1.26	1.89	15.3	12.1	1.79	.313	7.99	10.91
8	Royals	7.16	27	July 1999	.407	11	16	135	0	7	236.1	297	188	197	41	138	16	7	1,127	13	5.14	5.26	0.98	1.56	12.0	12.2	1.84	.321	7.50	11.31
9	Rockies	7.03	29	May 1993	.241	7	22	164	0	4	258.2	343	202	221	38	119	8	10	1,221	16	5.71	4.14	1.38	1.32	13.4	9.7	1.79	.342	7.69	11.93
10	Tigers	7.00	27	June 1996	.370	10	17	145	2	4	234.0	287	182	187	43	138	17	13	1,106	13	5.58	5.31	1.05	1.65	13.1	12.5	1.82	.320	7.19	11.04
11	Cubs	6.97	27	August 2021	.259	7	20	212	0	4	230.0	283	178	193	52	85	18	5	1,053	12	8.30	3.33	2.49	2.03	20.1	8.1	1.60	.337	7.55	11.07
12	Devil Rays	6.95	27	July 2007	.259	7	20	188	0	2	235.2	292	182	191	32	113	6	6	1,095	14	7.18	4.32	1.66	1.22	17.2	10.3	1.72	.344	7.29	11.15
13	Orioles	6.89	29	September 2007	.345	10	19	176	0	5	256.0	316	196	202	33	146	16	11	1,221	12	6.19	5.13	1.21	1.16	14.4	12.0	1.80	.333	7.10	11.11
14	Rockies	6.84	27	June 2023	.333	9	18	206	0	8	235.2	288	179	187	46	111	14	3	1,085	7	7.87	4.24	1.86	1.76	19.0	10.2	1.69	.342	7.14	11.00
15	Rockies	6.74	30	July 1999	.400	12	18	173	0	9	263.0	317	197	203	56	136	8	6	1,208	10	5.92	4.65	1.27	1.92	14.3	11.3	1.72	.313	6.95	10.85
16	Athletics	6.73	27	September 2015	.296	8	19	165	0	4	240.2	298	180	188	48	107	6	6	1,108	12	6.17	4.00	1.54	1.80	14.9	9.7	1.68	.320	7.03	11.14
17	Rangers	6.72	25	April 2001	.440	11	14	150	0	7	217.0	280	162	169	43	94	8	7	1,016	6	6.22	3.90	1.60	1.78	14.8	9.3	1.72	.329	7.01	11.61
18	Diamondbacks	6.69	28	August 2005	.321	9	19	175	0	3	242.0	291	180	196	45	106	14	11	1,121	16	6.51	3.94	1.65	1.67	15.6	9.5	1.64	.315	7.29	10.82
19	Blue Jays	6.69	24	April 2002	.333	8	16	163	0	3	216.2	258	161	172	37	105	13	8	1,015	17	6.77	4.36	1.55	1.54	16.1	10.3	1.68	.317	7.14	10.72
20	Rockies	6.68	26	June 1999	.500	13	13	165	0	5	229.0	289	170	190	44	119	13	9	1,081	18	6.48	4.68	1.39	1.73	15.3	11.0	1.78	.331	7.47	11.36
21	Orioles	6.67	28	August 2019	.321	9	19	209	0	4	243.0	291	180	189	59	90	7	4	1,098	16	7.74	3.33	2.32	2.19	19.0	8.2	1.57	.317	7.00	10.78
22	Rangers	6.65	28	September 2000	.429	12	16	139	0	9	245.0	306	181	199	35	131	16	6	1,162	9	5.11	4.81	1.06	1.29	12.0	11.3	1.78	.322	7.31	11.24
23	Browns	6.64	31	June 1950	.419	13	18	85	1	5	280.2	328	207	232	40	136	6		1,292	3	2.73	4.36	0.63	1.28	6.6	10.5	1.65	.281	7.44	10.52
24	Rockies	6.64	27	April 1998	.407	11	16	161	1	6	240.0	293	177	190	31	117	14	2	1,114	9	6.04	4.39	1.38	1.16	14.5	10.5	1.71	.331	7.13	10.99
25	Rangers	6.63	27	June 2003	.259	7	20	156	0	5	234.2	283	173	179	44	103	12	9	1,074	6	5.98	3.95	1.51	1.69	14.5	9.6	1.64	.315	6.87	10.85