I don't have anything for this season, but the San Diego Padres had the best record by a team after the All-Star Game in 2024, with a record of 43-20.

Interpreted as:

best MLB record after all star break this season

	TEAM	REC	SEASON	W%	G	W	L	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Padres	43-20	2024	.683	63	43	20	2,171	312	580	116	7	81	294	182	26	415	51	9	2,409	953	204	14	16	6	45	.267	.329	.439	.768
2	Dodgers	42-23	2024	.646	65	42	23	2,209	363	581	115	9	104	352	228	25	541	76	8	2,489	1,026	228	6	21	14	34	.263	.336	.464	.800
3	Diamondbacks	40-25	2024	.615	65	40	25	2,242	404	619	104	18	109	384	245	38	502	60	14	2,569	1,086	231	17	27	5	45	.276	.353	.484	.838
4	Tigers	39-26	2024	.600	65	39	26	2,180	269	510	102	16	63	259	198	14	626	32	10	2,409	833	181	1	16	5	35	.234	.300	.382	.682
5	Mets	40-27	2024	.597	67	40	27	2,235	303	539	103	6	86	288	208	42	613	37	7	2,507	912	195	2	20	4	40	.241	.315	.408	.723
6	Brewers	38-27	2024	.585	65	38	27	2,176	311	520	96	18	78	299	234	14	610	84	18	2,450	886	192	9	17	11	36	.239	.315	.407	.722
7	Astros	38-27	2024	.585	65	38	27	2,228	283	582	102	5	80	261	181	28	507	29	8	2,459	934	187	6	16	17	60	.261	.322	.419	.742
8	Cubs	36-28	2024	.563	64	36	28	2,176	321	550	106	13	70	305	219	18	497	65	11	2,437	892	189	8	16	9	34	.253	.324	.410	.734
9	Yankees	36-28	2024	.563	64	36	28	2,181	327	546	104	2	97	313	285	18	540	50	9	2,513	945	203	5	24	19	50	.250	.339	.433	.772
10	Braves	36-31	2024	.537	67	36	31	2,276	297	559	95	6	104	288	219	23	617	25	7	2,538	978	205	7	13	5	59	.246	.316	.430	.746
11	Royals	34-31	2024	.523	65	34	31	2,203	293	548	104	11	69	282	172	23	497	54	13	2,429	881	184	10	21	8	38	.249	.307	.400	.707
12	Mariners	33-31	2024	.516	64	33	31	2,127	297	494	99	3	76	280	252	58	612	66	10	2,463	827	178	7	19	7	44	.232	.327	.389	.716
13	Guardians	34-32	2024	.515	66	34	32	2,163	254	498	85	7	76	246	179	26	501	69	16	2,391	825	168	8	15	8	37	.230	.295	.381	.676
14	Giants	33-32	2024	.508	65	33	32	2,183	266	502	102	16	81	253	172	21	643	37	8	2,393	879	199	3	14	4	46	.230	.291	.403	.693
15	Cardinals	33-33	2024	.500	66	33	33	2,250	274	564	108	10	71	265	199	17	511	35	13	2,485	905	189	3	16	5	47	.251	.314	.402	.716
16	Phillies	33-33	2024	.500	66	33	33	2,263	307	577	129	8	80	294	181	27	566	49	8	2,489	962	217	7	11	7	48	.255	.316	.425	.741
17	Orioles	33-33	2024	.500	66	33	33	2,250	312	553	93	11	86	301	229	23	583	35	10	2,524	926	190	3	19	6	30	.246	.319	.412	.731
18	Athletics	32-32	2024	.500	64	32	32	2,167	253	527	103	7	74	243	186	18	553	45	12	2,392	866	184	6	15	3	45	.243	.306	.400	.706
19	Rangers	32-34	2024	.485	66	32	34	2,235	269	523	89	4	75	255	186	20	539	45	11	2,454	845	168	2	11	6	31	.234	.297	.378	.675
20	Rays	32-34	2024	.485	66	32	34	2,190	228	487	95	12	61	214	182	29	623	83	18	2,415	789	168	2	12	9	24	.222	.289	.360	.650
21	Reds	30-35	2024	.462	65	30	35	2,156	267	498	99	9	66	257	198	32	587	73	16	2,409	813	174	6	17	2	34	.231	.303	.377	.680
22	Blue Jays	29-36	2024	.446	65	29	36	2,213	277	552	119	13	69	266	193	36	519	27	7	2,463	904	201	4	17	13	43	.249	.318	.408	.726
23	Marlins	29-37	2024	.439	66	29	37	2,270	301	587	110	11	72	284	198	25	612	73	16	2,529	935	193	13	23	5	42	.259	.322	.412	.734
24	Twins	28-38	2024	.424	66	28	38	2,233	276	525	117	8	68	259	194	33	549	19	5	2,482	862	193	5	17	8	38	.235	.304	.386	.690
25	Pirates	28-38	2024	.424	66	28	38	2,224	263	532	104	6	61	254	184	29	620	57	9	2,456	831	171	4	15	5	37	.239	.304	.374	.677