which pitcher has the best era in a calendar month in at least 30 innings

36 pitchers are tied for the best ERA when pitching at least 30 innings in a month, with an ERA of 0.00. The first three are Orel Hershiser in September 1988, Dwight Gooden in September 1985 and Mack Allison in September 1912.

	NAME	ERA	IP	MONTH	G	W	L	W%	GS	SO	CG	SHO	SV	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	H/9
1	Orel Hershiser O. Hershiser	0.00	55.0	September 1988	6	5	0	1.000	6	34	5	5	0	30	0	0	0	9	0	0	3	201	1	5.56	1.47	3.78	0.00	16.9	4.5	0.71	.190	0.00	4.91
2	Dwight Gooden D. Gooden	0.00	44.0	September 1985	5	3	0	1.000	5	39	2	2	0	24	0	1	0	9	0	0	1	164	0	7.98	1.84	4.33	0.00	23.8	5.5	0.75	.207	0.20	4.91
3	Mack Allison M. Allison	0.00	41.0	September 1912	8	1	4	.200	5	10	2	1	1	44		21	1	11	4	3		175	5	2.20	2.41	0.91	0.22	5.7	6.3	1.34	.289	4.61	9.66
4	Ray Collins R. Collins	0.00	45.0	September 1912	5	3	2	.600	5	18	5	1	0	45		13	1	12	0	0		189	0	3.60	2.40	1.50	0.20	9.5	6.3	1.27	.278	2.60	9.00
5	Boardwalk Brown B. Brown	0.00	51.0	September 1912	9	5	1	.833	5	18	5	1	0	50		32	0	22	1	2		218	3	3.18	3.88	0.82	0.00	8.3	10.1	1.41	.282	5.65	8.82
6	Willie Mitchell W. Mitchell	0.00	42.1	September 1912	6	2	2	.500	4	30	2	0	1	37		18	0	12	3	2		177	0	6.38	2.55	2.50	0.00	16.9	6.8	1.16	.280	3.83	7.87
7	Eddie Plank E. Plank	0.00	55.0	September 1912	7	5	1	.833	5	25	4	1	1	33		13	0	21	1	2		218	2	4.09	3.44	1.19	0.00	11.5	9.6	0.98	.193	2.13	5.40
8	Carl Weilman C. Weilman	0.00	41.0	September 1912	6	2	3	.400	5	23	5	2	1	29		12	0	1	0	1			1	5.05	0.22	23.00	0.00		0.6	0.73	.218	2.63	6.37
9	Byron Houck B. Houck	0.00	42.1	August 1912	8	1	1	.500	3	17	1	0	1	37		16	1	18	1	5		173	4	3.61	3.83	0.94	0.21	9.8	10.4	1.30	.265	3.40	7.87
10	Ray Collins R. Collins	0.00	48.0	August 1912	7	4	2	.667	7	21	3	2	0	40		12	0	6	0	0		192	0	3.94	1.13	3.50	0.00	10.9	3.1	0.96	.242	2.25	7.50
11	Eddie Plank E. Plank	0.00	45.0	August 1912	6	4	2	.667	6	27	5	2	0	44		14	0	11	0	0		182	1	5.40	2.20	2.45	0.00	14.8	6.0	1.22	.306	2.80	8.80
12	Hugh Bedient H. Bedient	0.00	56.0	August 1912	8	4	1	.800	7	31	5	0	0	58		23	2	14	0	0		244	2	4.98	2.25	2.21	0.32	12.7	5.7	1.29	.284	3.70	9.32
13	Charley Hall C. Hall	0.00	39.0	August 1912	7	2	1	.667	1	15	0	0	0	39		15	1	10	1	6		159	0	3.46	2.31	1.50	0.23	9.4	6.3	1.26	.288	3.46	9.00
14	Ray Caldwell R. Caldwell	0.00	68.1	August 1912	9	4	3	.571	8	28	7	2	0	71		27	0	14	1	1			2	3.69	1.84	2.00	0.00		4.8	1.24	.285	3.56	9.35
15	Earl Hamilton E. Hamilton	0.00	62.1	August 1912	10	4	3	.571	7	27	6	1	0	39		23	1	22	3	2		248	1	3.90	3.18	1.23	0.14	10.9	8.9	0.98	.195	3.32	5.63
16	Walter Johnson W. Johnson	0.00	68.1	August 1912	12	8	2	.800	6	61	5	2	1	40		11	0	13	1	6			2	8.03	1.71	4.69	0.00		5.2	0.78	.230	1.45	5.27
17	Buck O'Brien B. O'Brien	0.00	59.2	July 1912	7	5	2	.714	6	20	6	1	0	41		13	1	7	1	1		223	1	3.02	1.06	2.86	0.15	9.0	3.1	0.80	.206	1.96	6.18
18	Eddie Plank E. Plank	0.00	44.0	July 1912	7	5	2	.714	5	14	4	0	0	39		19	0	13	0	2		179	1	2.86	2.66	1.08	0.00	7.8	7.3	1.18	.257	3.89	7.98
19	Joe Wood J. Wood	0.00	51.2	July 1912	7	5	1	.833	6	42	5	1	0	41		15	0	10	4	1		204	3	7.32	1.74	4.20	0.00	20.6	4.9	0.99	.277	2.61	7.14
20	Hippo Vaughn H. Vaughn	0.00	46.2	July 1912	7	4	0	1.000	5	34	3	0	0	39		16	0	22	2	2		195	7	6.56	4.24	1.55	0.00	17.4	11.3	1.31	.285	3.09	7.52
21	Jim Baskette J. Baskette	0.00	35.2	July 1912	6	1	2	.333	2	16	2	0	1	38		24	0	12	4	4		162	2	4.04	3.03	1.33	0.00	9.9	7.4	1.40	.292	6.06	9.59
22	Jean Dubuc J. Dubuc	0.00	63.0	July 1912	8	7	0	1.000	6	18	6	1	1	48		21	0	36	1	2			4	2.57	5.14	0.50	0.00		13.5	1.33	.227	3.00	6.86
23	Byron Houck B. Houck	0.00	70.2	July 1912	9	4	3	.571	8	32	7	0	0	58		32	0	25	4	1		294	1	4.08	3.18	1.28	0.00	10.9	8.5	1.17	.249	4.08	7.39
24	Tom Hughes T. Hughes	0.00	45.1	July 1912	7	3	2	.600	6	25	2	1	0	49		23	1	18	2	1		195	0	4.96	3.57	1.39	0.20	12.8	9.2	1.48	.322	4.57	9.73
25	Jack Powell J. Powell	0.00	53.2	July 1912	7	2	4	.333	6	14	5	0	0	58		28	1	8	1	1		226	1	2.35	1.34	1.75	0.17	6.2	3.5	1.23	.282	4.70	9.73