Brickyard Kennedy has allowed the most runs in a postseason game, with 10 runs in Game 5 of the 1903 World Series against the Boston Americans.

Interpreted as:

most runs allowed by a player in a playoff game

	NAME	R	DATE	TM		OPP	DEC	GS	ERA	SO	CG	SHO	SV	IP	H	ER	HR	BB	HBP	GF	IBB	TBF	WP
1	Brickyard Kennedy B. Kennedy	10	10/7/1903	PIT	vs	BSA	L	1	5.14	3	0	0	0	7.0	10	4	0	3	0	0	0	38	0
2	Jay Witasick J. Witasick	9	11/3/2001	NYY	@	ARI		0	54.00	4	0	0	0	1.1	10	8	0	0	0	0	0	14	1
3	Phil Niekro P. Niekro	9	10/4/1969	ATL	vs	NYM	L	1	4.50	4	0	0	0	8.0	9	4	0	4	0	0	1	36	0
4	Walter Johnson W. Johnson	9	10/15/1925	WSH	@	PIT	L	1	5.63	3	1	0	0	8.0	15	5	0	1	0	0	0	40	0
5	Mordecai Brown M. Brown	9	10/18/1910	CHC	@	PHA	L	1	9.00	6	0	0	0	7.0	13	7	0	4	0	0	0	38	0
6	Andy Coakley A. Coakley	9	10/12/1905	PHA	vs	NYG	L	1	3.00	2	1	0	0	9.0	9	3	0	5	1	0	1	40	0
7	Jack Flaherty J. Flaherty	8	10/18/2024	LAD	@	NYM	L	1	24.00	0	0	0	0	3.0	8	8	1	4	0	0	0	21	0
8	Grant Dayton G. Dayton	8	10/14/2020	ATL	vs	LAD		0	36.00	2	0	0	0	2.0	8	8	3	1	1	0	0	16	0
9	Johnny Cueto J. Cueto	8	10/19/2015	KCR	@	TOR	L	1	36.00	2	0	0	0	2.0	6	8	1	4	1	0	0	17	0
10	Clayton Kershaw C. Kershaw	8	10/3/2014	LAD	vs	STL	L	1	10.80	10	0	0	0	6.2	8	8	2	0	0	0	0	28	0
11	Matt Moore M. Moore	8	10/4/2013	TBR	@	BOS	L	1	14.54	4	0	0	0	4.1	8	7	0	2	1	0	1	25	1
12	C.J. Wilson	8	9/30/2011	TEX	vs	TBR	L	1	10.80	6	0	0	0	5.0	7	6	3	1	1	0	0	25	0
13	Josh Beckett J. Beckett	8	10/11/2008	BOS	@	TBR		1	16.62	5	0	0	0	4.1	9	8	3	1	0	0	0	22	0
14	Chad Billingsley C. Billingsley	8	10/10/2008	LAD	@	PHI	L	1	27.00	5	0	0	0	2.1	8	7	0	3	0	0	1	18	0
15	CC Sabathia	8	10/12/2007	CLE	@	BOS	L	1	16.62	3	0	0	0	4.1	7	8	0	5	1	0	1	24	0
16	Chien-Ming Wang C. Wang	8	10/4/2007	NYY	@	CLE	L	1	15.43	2	0	0	0	4.2	9	8	2	4	1	0	0	25	0
17	Matt Clement M. Clement	8	10/4/2005	BOS	@	CWS	L	1	21.60	0	0	0	0	3.1	7	8	3	0	2	0	0	18	0
18	Jake Peavy J. Peavy	8	10/4/2005	SDP	@	STL	L	1	16.62	3	0	0	0	4.1	8	8	2	3	0	0	2	23	1
19	David Wells D. Wells	8	10/5/2002	NYY	@	ANA	L	1	15.43	0	0	0	0	4.2	10	8	1	0	0	0	0	24	0
20	Paul Abbott P. Abbott	8	10/13/2001	SEA	@	CLE		0	24.00	3	0	0	0	3.0	9	8	3	5	0	0	0	22	0
21	Hideki Irabu H. Irabu	8	10/16/1999	NYY	@	BOS		0	13.50	3	0	0	0	4.2	13	7	2	0	0	0	0	27	0
22	Charles Nagy C. Nagy	8	10/11/1999	CLE	vs	BOS		1	21.00	2	0	0	0	3.0	6	7	2	2	0	0	1	17	0
23	Steve Reed S. Reed	8	10/10/1999	CLE	@	BOS		0	54.00	1	0	0	0	1.1	7	8	1	1	2	0	0	14	0
24	Greg Maddux G. Maddux	8	10/10/1996	ATL	vs	STL	L	1	4.05	3	0	0	0	6.2	9	3	1	2	0	0	1	32	1
25	Tom Glavine T. Glavine	8	10/13/1992	ATL	vs	PIT	L	1	63.00	0	0	0	0	1.0	6	7	2	0	1	0	0	11	0