Frank Thomas has the most bases on balls in an ALCS, with 10 bases on balls.

Interpreted as:

most walks by a player in a single alcs

	NAME	BB	SEASON	SERIES	TM	G	AB	R	H	2B	3B	HR	RBI	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Frank Thomas F. Thomas	10	1993	ALCS	CWS	6	17	2	6	0	0	1	3	0	5	0	0	27	9	1	0	0	2	0	.353	.593	.529	1.122
2	Willy Adames W. Adames	9	2020	ALCS	TBR	7	17	1	2	2	0	0	3	1	8	0	0	27	4	2	0	0	0	1	.118	.444	.235	.680
3	Manny Ramirez M. Ramirez	9	2007	ALCS	BOS	7	22	5	9	1	0	2	10	0	5	0	0	32	16	3	0	1	1	2	.409	.563	.727	1.290
4	Greg Bird G. Bird	8	2017	ALCS	NYY	7	20	2	5	2	0	1	2	0	8	0	0	28	10	3	0	0	1	0	.250	.464	.500	.964
5	Josh Hamilton J. Hamilton	8	2010	ALCS	TEX	6	20	6	7	1	0	4	7	0	4	3	0	28	20	5	0	0	5	1	.350	.536	1.000	1.536
6	Alex Rodriguez A. Rodriguez	8	2009	ALCS	NYY	6	21	6	9	2	0	3	6	0	3	1	0	30	20	5	0	1	3	0	.429	.567	.952	1.519
7	Lane Thomas L. Thomas	7	2024	ALCS	CLE	5	17	2	2	1	0	0	0	0	6	1	0	24	3	1	0	0	0	0	.118	.375	.176	.551
8	Alex Bregman A. Bregman	7	2019	ALCS	HOU	6	18	4	3	1	0	0	1	1	2	0	0	26	4	1	0	0	1	1	.167	.423	.222	.645
9	Alex Bregman A. Bregman	7	2018	ALCS	HOU	5	15	3	2	1	0	0	1	2	3	0	1	24	3	1	0	0	0	0	.133	.458	.200	.658
10	Jose Bautista J. Bautista	7	2015	ALCS	TOR	6	19	4	6	1	0	2	6	0	5	0	0	26	13	3	0	0	0	0	.316	.500	.684	1.184
11	Miguel Cabrera M. Cabrera	7	2011	ALCS	DET	6	20	5	8	4	0	3	7	0	6	1	0	27	21	7	0	0	2	0	.400	.556	1.050	1.606
12	Curtis Granderson C. Granderson	7	2010	ALCS	NYY	6	17	1	5	1	0	1	3	1	4	0	1	25	9	2	0	0	0	0	.294	.520	.529	1.049
13	Jason Bay J. Bay	7	2008	ALCS	BOS	7	24	3	7	1	0	1	4	1	8	0	0	32	11	2	0	0	1	0	.292	.469	.458	.927
14	Jorge Posada J. Posada	7	2004	ALCS	NYY	7	27	4	7	1	0	0	2	1	1	0	0	36	8	1	0	1	2	1	.259	.417	.296	.713
15	Bernie Williams B. Williams	7	1998	ALCS	NYY	6	21	4	8	1	0	0	5	0	4	1	1	28	9	1	0	0	0	1	.381	.536	.429	.964
16	Roberto Alomar R. Alomar	7	1997	ALCS	BAL	6	22	2	4	0	0	1	2	0	3	0	0	29	7	1	0	0	2	2	.182	.379	.318	.697
17	Rickey Henderson R. Henderson	7	1989	ALCS	OAK	5	15	8	6	1	1	2	5	1	0	8	0	23	15	4	0	0	0	0	.400	.609	1.000	1.609
18	Lou Whitaker L. Whitaker	7	1987	ALCS	DET	5	17	4	3	0	0	1	1	0	3	1	0	24	6	1	0	0	0	0	.176	.417	.353	.770
19	George Brett G. Brett	7	1985	ALCS	KCR	7	23	6	8	2	0	3	5	0	5	0	1	30	19	5	0	0	3	0	.348	.500	.826	1.326
20	Alex Bregman A. Bregman	6	2023	ALCS	HOU	7	26	6	6	1	1	3	5	0	4	0	0	32	18	5	0	0	0	0	.231	.375	.692	1.067
21	Jose Altuve J. Altuve	6	2020	ALCS	HOU	7	26	6	12	2	0	3	5	0	5	0	1	32	23	5	0	0	0	1	.462	.563	.885	1.447
22	Derek Jeter D. Jeter	6	2009	ALCS	NYY	6	27	5	7	0	0	2	3	0	5	0	1	33	13	2	0	0	1	1	.259	.394	.481	.875
23	David Ortiz D. Ortiz	6	2008	ALCS	BOS	7	26	3	4	1	1	1	4	0	9	0	0	32	10	3	0	0	1	0	.154	.313	.385	.697
24	Carlos Pena C. Pena	6	2008	ALCS	TBR	7	26	8	7	1	0	3	6	0	7	1	0	32	17	4	0	0	1	1	.269	.406	.654	1.060
25	David Ortiz D. Ortiz	6	2007	ALCS	BOS	7	24	7	7	3	0	1	3	1	5	0	0	33	13	4	0	2	0	2	.292	.424	.542	.966