Ed Cushman has the lowest WHIP in a season, with a WHIP of 0.36 in 1884.

Interpreted as:

lowest whip with a minimum of 1 IP per team game by a player single season

	NAME	WHIP	SEASON	TM	G	W	L	W%	GS	ERA	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	BABIP	RA	ERA-	FIP	FIP-	H/9	PRAA
1	Ed Cushman E. Cushman	0.36	1884	MIL	4	4	0	1.000	4	1.00	47	4	2	0	36.0	10	4	4	0	3		0		125	1	11.75	0.75	15.67	0.00	37.6	2.4		1.00	8	0.91	8	2.50	17.4
2	Lady Baldwin L. Baldwin	0.47	1884	MIL	2	1	1	.500	2	2.65	21	2	0	0	17.0	7	5	5	0	1		0		61	0	11.12	0.53	21.00	0.00	34.4	1.6		2.65	20	0.98	9	3.71	8.2
3	Pedro Martinez P. Martinez	0.74	2000	BOS	29	18	6	.750	29	1.74	284	7	4	0	217.0	128	42	44	17	32	14	0	0	817	1	11.78	1.33	8.88	0.71	34.8	3.9	.236	1.82	35	2.16	47	5.31	61.5
4	Kenta Maeda K. Maeda	0.75	2020	MIN	11	6	1	.857	11	2.70	80	0	0	0	66.2	40	20	20	9	10	0	0	0	248	0	10.80	1.35	8.00	1.21	32.3	4.0	.208	2.70	62	2.99	68	5.40	10.5
5	Guy Hecker G. Hecker	0.77	1882	LOU	13	6	6	.500	11	1.30	33	10	0	0	104.0	75	15	49	0	5		1		403	7	2.86	0.43	6.60	0.00	8.2	1.2		4.24	49	2.27	82	6.49	5.1
6	Walter Johnson W. Johnson	0.78	1913	WSH	48	36	7	.837	36	1.14	243	29	11	2	346.0	232	44	56	9	38	9	10		1,271	2	6.32	0.99	6.39	0.23	19.1	3.0	.229	1.46	39	1.90	63	6.03	42.3
7	Trevor Bauer T. Bauer	0.79	2020	CIN	11	5	4	.556	11	1.73	100	2	2	0	73.0	41	14	17	9	17	3	0	1	278	3	12.33	2.10	5.88	1.11	36.0	6.1	.215	2.10	36	2.87	61	5.05	14.1
8	Tim Keefe T. Keefe	0.80	1880	TRO	12	6	6	.500	12	0.86	39	12	0	0	105.0	68	10	27	0	16		0		397	1	3.34	1.37	2.44	0.00	9.8	4.0		2.31	35	2.25	91	5.83	3.6
9	Justin Verlander J. Verlander	0.80	2019	HOU	34	21	6	.778	34	2.58	300	2	1	0	223.0	137	64	66	36	42	6	0	0	847	4	12.11	1.70	7.14	1.45	35.4	5.0	.218	2.66	57	3.26	72	5.53	31.5
10	Henry Porter H. Porter	0.80	1884	MIL	6	3	3	.500	6	3.00	71	6	1	0	51.0	32	17	25	1	9		0		200	6	12.53	1.59	7.89	0.18	35.5	4.5		4.41	23	1.27	11	5.65	24.1
11	Addie Joss A. Joss	0.81	1908	CLE	42	24	11	.686	35	1.16	130	29	9	2	325.0	232	42	77	2	30	2	6		1,209	6	3.60	0.83	4.33	0.06	10.8	2.5	.220	2.13	49	1.68	76	6.42	19.3
12	Greg Maddux G. Maddux	0.81	1995	ATL	28	19	2	.905	28	1.63	181	10	3	0	209.2	147	38	39	8	23	4	0	3	785	1	7.77	0.99	7.87	0.34	23.1	2.9	.244	1.67	39	2.25	52	6.31	46.9
13	Charlie Sweeney C. Sweeney	0.82	1884	TOT	60	41	15	.732	56	1.70	337	53	6	1	492.0	360	93	182	6	42		4		1,909	21	6.16	0.77	8.02	0.11	17.7	2.2		3.33	58	2.32	81	6.59	26.9
14	Ed Walsh E. Walsh	0.82	1910	CWS	45	18	20	.474	36	1.27	258	33	7	5	369.2	242	52	87	5	61	4	7		1,359	6	6.28	1.49	4.23	0.12	19.0	4.5	.230	2.12	52	1.63	66	5.89	34.8
15	Christy Mathewson C. Mathewson	0.83	1908	NYG	56	37	11	.771	44	1.43	259	34	11	5	390.2	281	62	85	5	42	3	9		1,469	2	5.97	0.97	6.17	0.12	17.6	2.9	.238	1.96	61	1.29	52	6.47	52.4
16	Christy Mathewson C. Mathewson	0.83	1909	NYG	37	25	6	.806	33	1.14	149	26	8	2	275.1	192	35	57	2	36	0	4		998	4	4.87	1.18	4.14	0.07	14.9	3.6	.234	1.86	44	1.62	61	6.28	31.7
17	Justin Verlander J. Verlander	0.83	2022	HOU	28	18	4	.818	28	1.75	185	0	0	0	175.0	116	34	43	12	29	6	0	0	666	3	9.51	1.49	6.38	0.62	27.8	4.4	.240	2.21	46	2.48	64	5.97	27.7
18	George Bradley G. Bradley	0.84	1880	PRO	28	13	8	.619	20	1.38	54	16	4	2	196.0	158	30	66	2	6		7		757	7	2.48	0.28	9.00	0.09	7.1	0.8		3.03	60	2.21	96	7.26	0.6
19	Mordecai Brown M. Brown	0.84	1908	CHC	44	29	9	.763	31	1.47	123	27	9	5	312.1	214	51	64	1	49	5	12		1,153	6	3.54	1.41	2.51	0.03	10.7	4.2	.218	1.84	63	1.87	75	6.17	21.5
20	Grover Alexander G. Alexander	0.84	1915	PHN	49	31	10	.756	42	1.22	241	36	12	3	376.1	253	51	86	3	64	10	7		1,435	2	5.76	1.53	3.77	0.07	16.8	4.5	.224	2.06	43	1.82	63	6.05	44.1
21	Dave McNally D. McNally	0.84	1968	BAL	35	22	10	.688	35	1.95	202	18	5	0	273.0	175	59	67	24	55	10	0	1	1,038	5	6.66	1.81	3.67	0.79	19.5	5.3	.202	2.21	67	2.76	90	5.77	9.5
22	Zack Greinke Z. Greinke	0.84	2015	LAD	32	19	3	.864	32	1.66	200	1	0	0	222.2	148	41	43	14	40	5	0	1	843	7	8.08	1.62	5.00	0.57	23.7	4.7	.229	1.74	44	2.75	73	5.98	26.2
23	Henry Boyle H. Boyle	0.85	1884	SLU	19	15	3	.833	16	1.74	88	16	2	1	150.0	118	29	63	3	10		3		595	3	5.28	0.60	8.80	0.18	14.8	1.7		3.78	59	2.56	100	7.08	-1.1
24	Bob Gibson B. Gibson	0.85	1968	STL	34	22	9	.710	34	1.12	268	28	13	0	304.2	198	38	49	11	62	7	0	6	1,161	4	7.92	1.83	4.32	0.32	23.1	5.3	.230	1.45	38	1.77	63	5.85	34.8
25	Sandy Koufax S. Koufax	0.86	1965	LAD	43	26	8	.765	41	2.04	382	27	8	2	335.2	216	76	90	26	71	5	2	4	1,297	11	10.24	1.90	5.38	0.70	29.5	5.5	.234	2.41	63	1.93	61	5.79	47.9