Christy Mathewson has the best career ERA in the postseason when starting 10+ games, with an ERA of 1.06.

Interpreted as:

Best playoff era by a player with 10+ starts

	NAME	ERA	GS	G	W	L	W%	SO	CG	SHO	SV	IP	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	Christy Mathewson C. Mathewson	1.06	11	11	5	5	.500	48	10	4	0	101.2	76	12	22	1	10	1	0	3	391	1	4.25	0.89	4.80	0.09	12.3	2.6	0.85	.227	1.95	6.73
2	Waite Hoyt W. Hoyt	1.83	11	12	6	4	.600	49	6	1	0	83.2	81	17	28	2	22	1	1	0	345	0	5.27	2.37	2.23	0.22	14.2	6.4	1.23	.292	3.01	8.71
3	Madison Bumgarner M. Bumgarner	2.11	14	16	8	3	.727	87	3	3	1	102.1	74	24	25	8	18	5	1	2	398	0	7.65	1.58	4.83	0.70	21.9	4.5	0.90	.236	2.20	6.51
4	Zack Wheeler Z. Wheeler	2.18	11	12	4	3	.571	77	0	0	0	70.1	37	17	19	5	14	5	0	0	264	1	9.85	1.79	5.50	0.64	29.2	5.3	0.73	.196	2.43	4.73
5	Curt Schilling C. Schilling	2.23	19	19	11	2	.846	120	4	2	0	133.1	104	33	37	12	25	3	0	0	525	1	8.10	1.69	4.80	0.81	22.9	4.8	0.97	.252	2.50	7.02
6	Ken Holtzman K. Holtzman	2.30	12	13	6	4	.600	39	2	1	0	70.1	61	18	22	2	18	0	0	1	286	1	4.99	2.30	2.17	0.26	13.6	6.3	1.12	.260	2.82	7.81
7	Chief Bender C. Bender	2.44	10	10	6	4	.600	59	9	1	0	85.0	64	23	28	1	21	2	0	0	331	1	6.25	2.22	2.81	0.11	17.8	6.3	1.00	.254	2.96	6.78
8	Dave McNally D. McNally	2.49	12	14	7	4	.636	65	6	2	0	90.1	65	25	30	12	34	1	2	2	364	5	6.48	3.39	1.91	1.20	17.9	9.3	1.10	.210	2.99	6.48
9	Jon Lester J. Lester	2.51	22	26	9	7	.563	133	0	0	0	154.0	117	43	46	15	40	3	2	0	610	4	7.77	2.34	3.33	0.88	21.8	6.6	1.02	.243	2.69	6.84
10	Cliff Lee C. Lee	2.52	11	11	7	3	.700	89	3	0	0	82.0	66	23	27	2	10	1	0	0	320	2	9.77	1.10	8.90	0.22	27.8	3.1	0.93	.294	2.96	7.24
11	Orlando Hernandez O. Hernandez	2.55	14	19	9	3	.750	107	0	0	0	106.0	77	30	32	10	55	4	0	3	443	1	9.08	4.67	1.95	0.85	24.2	12.4	1.25	.251	2.72	6.54
12	Orel Hershiser O. Hershiser	2.59	18	22	8	3	.727	97	4	2	1	132.0	103	38	43	8	43	6	2	5	533	6	6.61	2.93	2.26	0.55	18.2	8.1	1.11	.251	2.93	7.02
13	Jim Palmer J. Palmer	2.61	15	17	8	3	.727	90	6	2	0	124.1	101	36	36	10	50	2	1	4	518	6	6.51	3.62	1.80	0.72	17.4	9.7	1.21	.249	2.61	7.31
14	Red Ruffing R. Ruffing	2.63	10	10	7	2	.778	61	8	0	0	85.2	74	25	32	4	27	0	0	2	352	0	6.41	2.84	2.26	0.42	17.3	7.7	1.18	.269	3.36	7.77
15	Tommy John T. John	2.65	13	14	6	3	.667	48	3	1	0	88.1	82	26	36	6	24	4	1	1	367	4	4.89	2.45	2.00	0.61	13.1	6.5	1.20	.267	3.67	8.35
16	John Smoltz J. Smoltz	2.67	27	41	15	4	.789	199	2	1	4	209.0	172	62	67	17	67	3	11	6	856	6	8.57	2.89	2.97	0.73	23.2	7.8	1.14	.272	2.89	7.41
17	Whitey Ford W. Ford	2.71	22	22	10	8	.556	94	7	3	0	146.0	132	44	51	8	34	3	0	2	594	4	5.79	2.10	2.76	0.49	15.8	5.7	1.14	.273	3.14	8.14
18	Gerrit Cole G. Cole	2.77	22	22	11	6	.647	156	0	0	0	133.1	100	41	50	19	36	3	0	1	537	1	10.53	2.43	4.33	1.28	29.1	6.7	1.02	.251	3.38	6.75
19	Adam Wainwright A. Wainwright	2.83	16	29	4	5	.444	123	1	0	4	114.1	105	36	39	11	22	2	9	1	464	4	9.68	1.73	5.59	0.87	26.5	4.7	1.11	.307	3.07	8.27
20	Barry Zito B. Zito	2.83	10	10	6	3	.667	46	0	0	0	60.1	50	19	19	7	23	3	0	1	252	1	6.86	3.43	2.00	1.04	18.3	9.1	1.21	.249	2.83	7.46
21	Dave Stewart D. Stewart	2.84	18	22	10	6	.625	73	3	1	0	133.0	99	42	45	13	48	4	3	1	539	4	4.94	3.25	1.52	0.88	13.5	8.9	1.11	.214	3.05	6.70
22	Mike Cuellar M. Cuellar	2.85	12	12	4	4	.500	56	4	0	0	85.1	66	27	32	7	31	0	0	3	349	1	5.91	3.27	1.81	0.74	16.0	8.9	1.14	.231	3.38	6.96
23	Steve Avery S. Avery	2.90	12	18	5	3	.625	60	0	0	0	77.2	61	25	28	6	29	0	2	5	312	3	6.95	3.36	2.07	0.70	19.2	9.3	1.16	.253	3.24	7.07
24	Anibal Sanchez A. Sanchez	2.93	10	11	3	6	.333	64	0	0	0	61.1	51	20	22	9	19	2	0	1	256	4	9.39	2.79	3.37	1.32	25.0	7.4	1.14	.259	3.23	7.48
25	Chris Carpenter C. Carpenter	3.00	18	18	10	4	.714	68	1	1	0	108.0	104	36	43	11	36	6	0	2	461	1	5.67	3.00	1.89	0.92	14.8	7.8	1.30	.274	3.58	8.67