Starling Marte stole the most bases in a month in 2021, with 19 steals in August 2021.

Interpreted as:

most sb by a player in a month in 2021

	NAME	SB	MONTH	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Starling Marte S. Marte	19	August 2021	26	113	17	41	9	0	2	14	4	1	19	0	119	56	11	0	1	0	1	.363	.387	.496	.882
2	Adalberto Mondesi A. Mondesi	13	September 2021	22	79	10	14	1	1	2	7	4	1	29	0	86	23	4	2	0	0	1	.177	.226	.291	.517
3	Whit Merrifield W. Merrifield	11	August 2021	28	119	20	36	6	1	2	14	7	1	18	2	128	50	9	0	1	0	2	.303	.344	.420	.764
4	Starling Marte S. Marte	11	July 2021	23	85	18	25	4	0	1	7	10	4	24	1	100	32	5	1	0	1	0	.294	.394	.376	.770
5	Nicky Lopez N. Lopez	10	August 2021	27	104	13	33	3	0	1	11	7	1	19	0	117	39	4	5	0	0	3	.317	.366	.375	.741
6	Ronald Acuña Jr. R. Acuña Jr.	10	June 2021	26	95	24	26	10	0	6	15	17	3	36	3	116	54	16	0	1	0	0	.274	.397	.568	.965
7	Starling Marte S. Marte	9	June 2021	26	96	20	28	3	0	4	10	14	1	20	1	111	43	7	0	0	1	1	.292	.387	.448	.835
8	Jazz Chisholm Jr. J. Chisholm Jr.	9	April 2021	22	74	12	23	6	1	4	8	9	1	26	0	85	43	11	0	1	0	0	.311	.388	.581	.969
9	David Fletcher D. Fletcher	8	August 2021	29	121	11	28	3	1	0	4	7	0	9	1	128	33	4	0	0	0	2	.231	.273	.273	.546
10	José Ramírez J. Ramírez	8	August 2021	27	110	20	30	8	2	9	22	13	0	15	0	123	69	19	0	0	1	0	.273	.350	.627	.977
11	Raimel Tapia R. Tapia	8	July 2021	21	72	11	20	3	0	0	5	9	0	12	0	83	23	3	1	1	0	2	.278	.354	.319	.673
12	Ozzie Albies O. Albies	8	June 2021	28	112	18	36	10	2	6	29	8	0	24	2	120	68	18	0	0	0	1	.321	.367	.607	.974
13	Fernando Tatis Jr. F. Tatis Jr.	8	May 2021	20	68	21	24	5	0	9	26	13	0	18	1	84	56	14	0	3	4	2	.353	.440	.824	1.264
14	Ramón Laureano R. Laureano	8	April 2021	24	94	13	21	4	2	3	9	6	3	27	3	103	38	9	0	0	0	0	.223	.291	.404	.696
15	Whit Merrifield W. Merrifield	8	April 2021	24	95	16	26	4	0	3	15	7	1	10	1	107	39	7	0	4	1	0	.274	.318	.411	.728
16	Yonny Hernández Y. Hernández	7	September 2021	21	67	7	13	2	0	0	2	11	0	18	1	79	15	2	1	0	0	2	.194	.308	.224	.532
17	José Ramírez J. Ramírez	7	September 2021	29	96	22	28	4	1	5	16	18	0	16	0	116	49	10	0	2	2	2	.292	.397	.510	.907
18	Adolis García A. García	7	September 2021	25	102	9	22	5	0	2	13	3	1	33	1	108	33	7	0	2	0	5	.216	.241	.324	.564
19	Myles Straw M. Straw	7	September 2021	28	106	16	32	6	0	0	4	16	0	23	1	122	38	6	0	0	0	2	.302	.393	.358	.752
20	Tommy Edman T. Edman	7	September 2021	28	120	16	30	6	0	1	9	4	1	26	0	128	39	7	1	2	0	0	.250	.276	.325	.601
21	Cedric Mullins C. Mullins	7	August 2021	26	103	17	26	3	0	7	12	7	2	25	0	114	50	10	1	1	0	0	.252	.310	.485	.795
22	Tyler Wade T. Wade	7	August 2021	19	35	10	16	4	0	0	3	6	1	9	1	42	20	4	0	0	0	0	.457	.548	.571	1.119
23	Shohei Ohtani S. Ohtani	7	August 2021	29	94	16	19	2	1	5	8	21	0	35	2	116	38	8	0	1	5	2	.202	.345	.404	.749
24	Fernando Tatis Jr. F. Tatis Jr.	7	July 2021	25	91	19	25	6	0	6	15	9	0	31	1	100	49	12	0	0	1	1	.275	.340	.538	.878
25	Whit Merrifield W. Merrifield	7	June 2021	27	114	16	40	6	2	4	17	5	0	19	0	120	62	12	0	1	0	1	.351	.375	.544	.919