Karl Spooner has the highest career ERA in the postseason, with an ERA of 135.00.

Interpreted as:

highest single game playoff era by a player

	NAME	ERA	G	W	L	W%	GS	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	Karl Spooner K. Spooner	135.00	1	0	1	.000	1	1	0	0	0	0.1	3	5	5	1	2	0	0	0	6	0	27.00	54.00	0.50	27.00	16.7	33.3	15.00	1.000	135.00	81.00
2	Kameron Loe K. Loe	108.00	1	0	0		0	0	0	0	0	0.1	6	4	4	0	0	0	0	0	7	0	0.00	0.00		0.00	0.0	0.0	18.00	.857	108.00	162.00
3	Dennis Lamp D. Lamp	108.00	1	0	0		0	0	0	0	0	0.1	2	4	4	0	2	0	0	1	5	0	0.00	54.00	0.00	0.00	0.0	40.0	12.00	.667	108.00	54.00
4	Vinegar Bend Mizell V. Bend Mizell	108.00	1	0	1	.000	1	0	0	0	0	0.1	3	4	4	0	1	0	0	0	5	0	0.00	27.00	0.00	0.00	0.0	20.0	12.00	.750	108.00	81.00
5	Harry McIntire H. McIntire	108.00	1	0	1	.000	0	0	0	0	0	0.1	3	4	4	1	0	1	0	0	5	0	0.00	0.00		27.00	0.0	0.0	9.00	.667	108.00	81.00
6	Bryan Baker B. Baker	81.00	1	0	0		0	0	0	0	0	0.1	0	3	3	0	3	0	0	0	4	0	0.00	81.00	0.00	0.00	0.0	75.0	9.00	.000	81.00	0.00
7	Aaron Civale A. Civale	81.00	1	0	1	.000	1	1	0	0	0	0.1	2	3	3	1	1	1	0	0	5	0	27.00	27.00	1.00	27.00	20.0	20.0	9.00	1.000	81.00	54.00
8	Aaron Bummer A. Bummer	81.00	1	0	1	.000	0	1	0	0	0	0.1	3	3	3	0	0	0	0	0	4	0	27.00	0.00		0.00	25.0	0.0	9.00	1.000	81.00	81.00
9	Chad Sobotka C. Sobotka	81.00	1	0	0		0	0	0	0	0	0.1	2	3	3	1	2	0	0	0	5	0	0.00	54.00	0.00	27.00	0.0	40.0	12.00	.500	81.00	54.00
10	Jose Arredondo J. Arredondo	81.00	1	0	0		0	0	0	0	0	0.1	3	3	3	1	1	0	0	0	5	0	0.00	27.00	0.00	27.00	0.0	20.0	12.00	.667	81.00	81.00
11	Michael Stutes M. Stutes	81.00	1	0	0		0	0	0	0	0	0.1	3	3	3	0	1	0	0	0	5	0	0.00	27.00	0.00	0.00	0.0	20.0	12.00	.750	81.00	81.00
12	Brian Kingman B. Kingman	81.00	1	0	0		0	0	0	0	0	0.1	3	3	3	0	0	0	0	0	4	0	0.00	0.00		0.00	0.0	0.0	9.00	.750	81.00	81.00
13	Brock Burke B. Burke	67.50	2	0	0		0	0	0	0	0	0.2	4	5	5	0	1	0	0	0	7	0	0.00	13.50	0.00	0.00	0.0	14.3	7.50	.667	67.50	54.00
14	Brandon Workman B. Workman	67.50	2	0	0		0	2	0	0	0	0.2	5	5	5	2	3	0	0	0	10	0	27.00	40.50	0.67	27.00	20.0	30.0	12.00	1.000	67.50	67.50
15	Tommy Nance T. Nance	54.00	1	0	0		0	0	0	0	0	0.1	3	2	2	0	0	0	0	0	4	0	0.00	0.00		0.00	0.0	0.0	9.00	.750	54.00	81.00
16	Justin Bruihl J. Bruihl	54.00	1	0	0		0	0	0	0	0	0.1	3	2	2	1	0	0	0	0	4	0	0.00	0.00		27.00	0.0	0.0	9.00	.667	54.00	81.00
17	J.P. France	54.00	1	0	0		0	1	0	0	0	0.2	5	4	4	0	1	0	0	0	8	0	13.50	13.50	1.00	0.00	12.5	12.5	9.00	.833	54.00	67.50
18	Bailey Falter B. Falter	54.00	1	0	0		1	0	0	0	0	0.2	3	4	4	1	1	0	0	0	6	0	0.00	13.50	0.00	13.50	0.0	16.7	6.00	.500	54.00	40.50
19	Connor Brogdon C. Brogdon	54.00	1	0	0		0	0	0	0	0	0.1	2	2	2	0	2	0	0	0	5	0	0.00	54.00	0.00	0.00	0.0	40.0	12.00	.667	54.00	54.00
20	Mychal Givens M. Givens	54.00	1	0	0		0	1	0	0	0	0.1	1	2	2	0	1	0	0	0	3	0	27.00	27.00	1.00	0.00	33.3	33.3	6.00	1.000	54.00	27.00
21	J.B. Wendelken	54.00	1	0	0		0	0	0	0	0	0.1	1	2	2	1	1	0	0	0	3	0	0.00	27.00	0.00	27.00	0.0	33.3	6.00	.000	54.00	27.00
22	Pierce Johnson P. Johnson	54.00	1	0	0		0	0	0	0	0	0.1	1	2	2	0	1	0	0	0	3	0	0.00	27.00	0.00	0.00	0.0	33.3	6.00	.500	54.00	27.00
23	Génesis Cabrera G. Cabrera	54.00	1	0	0		0	1	0	0	0	0.1	0	2	2	0	2	0	0	0	3	0	27.00	54.00	0.50	0.00	33.3	66.7	6.00		54.00	0.00
24	Raisel Iglesias R. Iglesias	54.00	2	0	0		0	1	0	0	0	0.2	5	4	5	2	3	0	0	0	10	0	13.50	40.50	0.33	27.00	10.0	30.0	12.00	.750	67.50	67.50
25	A.J. Cole	54.00	1	0	0		0	1	0	0	0	0.1	1	2	2	1	1	0	0	0	3	0	27.00	27.00	1.00	27.00	33.3	33.3	6.00		54.00	27.00