I didn't find anything for this season, but Ketel Marte had the highest OPS with 40+ at-bats in the 9th inning in 2024, with an OPS of 1.449.

Interpreted as:

highest ops by a player min 40 ab in the 9th inning this regular season

	NAME	OPS	AB	SEASON	TM	G	H	2B	3B	HR	RBI	BB	HBP	SO	PA	TB	XBH	SH	SF	IBB	AVG	OBP	SLG
1	Ketel Marte K. Marte	1.449	43	2024	ARI	47	17	0	0	9	19	3	0	10	47	44	9	0	1	1	.395	.426	1.023
2	Shea Langeliers S. Langeliers	1.432	42	2024	OAK	44	17	1	0	8	14	2	0	7	44	42	9	0	0	0	.405	.432	1.000
3	Bobby Witt Jr. B. Witt Jr.	1.100	43	2024	KCR	53	15	2	2	2	13	9	1	6	53	27	6	0	0	2	.349	.472	.628
4	Michael Busch M. Busch	1.039	45	2024	CHC	56	13	2	0	4	8	12	0	16	57	27	6	0	0	1	.289	.439	.600
5	Marcell Ozuna M. Ozuna	1.029	43	2024	ATL	45	15	1	0	4	7	2	0	10	45	28	5	0	0	0	.349	.378	.651
6	Otto Lopez O. Lopez	1.028	43	2024	MIA	45	16	5	0	2	6	2	0	10	45	27	7	0	0	0	.372	.400	.628
7	William Contreras W. Contreras	.984	45	2024	MIL	48	17	2	0	2	10	4	0	6	49	25	4	0	0	2	.378	.429	.556
8	Pete Alonso P. Alonso	.974	49	2024	NYM	56	12	2	0	6	12	4	2	12	56	32	8	0	1	0	.245	.321	.653
9	Tyler Stephenson T. Stephenson	.950	45	2024	CIN	51	14	3	0	3	6	4	1	14	51	26	6	0	1	0	.311	.373	.578
10	Wyatt Langford W. Langford	.950	40	2024	TEX	45	13	3	0	2	11	4	1	4	45	22	5	0	0	0	.325	.400	.550
11	Cedric Mullins C. Mullins	.934	50	2024	BAL	58	16	4	0	2	9	7	1	10	58	26	6	0	0	0	.320	.414	.520
12	Colt Keith C. Keith	.931	45	2024	DET	51	12	2	0	4	6	6	0	8	51	26	6	0	0	0	.267	.353	.578
13	Yainer Diaz Y. Diaz	.907	47	2024	HOU	48	16	4	0	2	5	1	0	6	48	26	6	0	0	0	.340	.354	.553
14	Nick Castellanos N. Castellanos	.906	46	2024	PHI	47	15	3	1	2	8	1	0	10	47	26	6	0	0	0	.326	.340	.565
15	Oneil Cruz O. Cruz	.893	48	2024	PIT	56	16	3	1	1	10	5	1	11	56	24	5	0	2	3	.333	.393	.500
16	Jo Adell J. Adell	.888	45	2024	LAA	53	12	3	1	2	10	5	3	15	53	23	6	0	0	0	.267	.377	.511
17	Gunnar Henderson G. Henderson	.887	41	2024	BAL	48	11	2	1	2	8	6	1	7	48	21	5	0	0	1	.268	.375	.512
18	Kyle Schwarber K. Schwarber	.877	41	2024	PHI	47	10	3	0	3	5	6	0	13	47	22	6	0	0	2	.244	.340	.537
19	Matt Chapman M. Chapman	.867	57	2024	SFG	67	14	3	0	4	5	8	2	19	67	29	7	0	0	0	.246	.358	.509
20	Cal Raleigh C. Raleigh	.866	41	2024	SEA	48	10	2	0	3	8	7	0	13	48	21	5	0	0	0	.244	.354	.512
21	Luis Arraez L. Arraez	.852	50	2024	TOT	51	19	4	0	0	3	1	0	0	51	23	4	0	0	0	.380	.392	.460
22	Rafael Devers R. Devers	.831	45	2024	BOS	47	12	1	1	3	7	2	0	12	47	24	5	0	0	0	.267	.298	.533
23	Teoscar Hernández T. Hernández	.820	40	2024	LAD	44	9	1	1	3	9	2	2	15	44	21	5	0	0	0	.225	.295	.525
24	Seiya Suzuki S. Suzuki	.818	45	2024	CHC	51	13	3	0	1	8	7	1	13	53	19	4	0	0	1	.289	.396	.422
25	Francisco Lindor F. Lindor	.818	60	2024	NYM	62	16	3	0	4	11	3	0	11	63	31	7	0	0	0	.267	.302	.517