what is the worst record in a calendar month by a team that went on to lead the nl in wins

The New York Giants had a 29-5 record in the NL in September 1916.

	TEAM	REC	W	MONTH	W%	L	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Giants	29-5	29	September 1916	.853	5	36	1,130	154	302	41	17	13	126	80	7	127	54		1,247	416	71	30				.267	.320	.368	.688
2	Cubs	26-8	26	July 1935	.765	8	34	1,265	236	390	82	10	24	219	98	8	81	25		1,404	564	116	33				.308	.362	.446	.808
3	Cardinals	26-7	26	July 1944	.788	7	33	1,180	190	346	64	16	19	177	110	6	78	8		1,329	499	99	33			22	.293	.356	.423	.779
4	Cubs	26-6	26	July 1945	.813	6	32	1,115	183	341	58	11	11	166	128	6	87	14		1,278	454	80	29			16	.306	.380	.407	.787
5	Braves	26-5	26	September 1914	.839	5	34	1,112	183	309	64	13	5		121	13	133	26		1,304	414	82	58				.278	.356	.372	.728
6	Cubs	26-3	26	August 1906	.897	3	29	883	140	244	29	10	2		92	8		38		1,039	299	41	56				.276	.350	.339	.689
7	Pirates	25-13	25	July 1932	.658	13	38	1,369	192	404	65	21	12	175	88	9	97	10		1,492	547	98	26				.295	.342	.400	.741
8	Dodgers	25-8	25	July 1947	.758	8	34	1,141	195	327	57	14	18	181	168	6	117	18		1,349	466	89	34			21	.287	.381	.408	.789
9	Cardinals	25-8	25	August 1942	.758	8	34	1,213	171	332	57	13	10	154	121	4	108	24		1,364	445	80	26			23	.274	.342	.367	.708
10	Giants	25-8	25	September 1928	.758	8	33	1,193	184	367	58	10	28	174	93	11	79	11		1,335	529	96	38				.308	.363	.443	.807
11	Pirates	25-8	25	September 1908	.758	8	33	1,106	155	294	30	14	4		91	13		50		1,258	364	48	48				.266	.329	.329	.658
12	Pirates	25-7	25	September 1901	.781	7	32	1,137	226	363	59	22	8	197	115	14	76	37		1,289	490	89	23				.319	.389	.431	.820
13	Dodgers	25-6	25	August 1953	.806	6	31	1,086	206	330	48	9	49	199	139	5	140	12	13	1,246	543	106	16			25	.304	.385	.500	.885
14	Giants	25-6	25	July 1913	.806	6	31	1,020	140	289	51	14	7	126	90	18	84	59		1,150	389	72	22				.283	.352	.381	.733
15	Cardinals	24-9	24	September 1939	.727	9	34	1,222	196	386	79	15	21	187	87	6	126	3		1,359	558	115	44			30	.316	.364	.457	.821
16	Cubs	24-8	24	July 1929	.750	8	33	1,171	239	387	78	13	35	226	114	4	106	15		1,322	596	126	33				.330	.392	.509	.901
17	Giants	24-8	24	September 1908	.750	8	33	1,062	152	312	56	10	3	137	117	13		46		1,242	397	69	50				.294	.371	.374	.745
18	Reds	24-7	24	July 1973	.774	7	31	1,027	150	267	48	10	31	144	132	7	165	29	9	1,188	428	89	9	13	22	17	.260	.344	.417	.761
19	Cardinals	24-7	24	July 1943	.774	7	31	1,090	157	322	56	10	12	150	95	6	83	8		1,225	434	78	34			16	.295	.355	.398	.753
20	Pirates	24-7	24	July 1938	.774	7	32	1,135	167	331	70	10	12	157	108	4	75	10		1,267	457	92	20				.292	.355	.403	.758
21	Cardinals	24-6	24	July 1968	.800	6	30	1,018	127	283	51	11	8	120	74	6	169	27	11	1,131	380	70	15	18	13	18	.278	.325	.373	.699
22	Dodgers	24-5	24	August 2023	.828	5	29	989	176	290	71	1	44	173	107	13	214	23	5	1,123	495	116	1	13	6	23	.293	.365	.501	.866
23	Giants	24-4	24	June 1954	.857	4	28	969	139	261	41	4	30	136	98	8	112	9	7	1,100	400	75	15	10		17	.269	.338	.413	.751
24	Giants	24-3	24	August 1936	.889	3	27	976	141	287	31	6	21	133	69	5	73	9		1,074	393	58	24				.294	.344	.403	.746
25	Braves	23-13	23	August 1947	.639	13	36	1,227	173	332	54	10	16	161	144	2	114	12		1,411	454	80	38			26	.271	.348	.370	.718