Between the 1989 and 2020 seasons, Andy Pettitte had the most wins in the postseason, with 19 wins.

Interpreted as:

most MLB playoff wins by a player from 1989 to 2020

	NAME	W	L	W%	G	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%	WHIP	BABIP	RA	H/9
1	Andy Pettitte A. Pettitte	19	11	.633	44	44	3.81	183	0	0	0	276.2	285	117	121	31	76	3	0	4	1,157	4	5.95	2.47	2.41	1.01	15.8	6.6	1.30	.294	3.94	9.27
2	John Smoltz J. Smoltz	15	4	.789	41	27	2.67	199	2	1	4	209.0	172	62	67	17	67	3	11	6	856	6	8.57	2.89	2.97	0.73	23.2	7.8	1.14	.272	2.89	7.41
3	Justin Verlander J. Verlander	14	11	.560	31	30	3.40	205	2	1	0	187.2	140	71	74	26	60	3	0	0	754	8	9.83	2.88	3.42	1.25	27.2	8.0	1.07	.248	3.55	6.71
4	Tom Glavine T. Glavine	14	16	.467	35	35	3.30	143	3	0	0	218.1	191	80	91	21	87	7	0	11	912	3	5.89	3.59	1.64	0.87	15.7	9.5	1.27	.260	3.75	7.87
5	Clayton Kershaw C. Kershaw	13	12	.520	37	30	4.19	207	0	0	1	189.0	153	88	93	28	50	4	2	5	759	10	9.86	2.38	4.14	1.33	27.3	6.6	1.07	.266	4.43	7.29
6	Curt Schilling C. Schilling	11	2	.846	19	19	2.23	120	4	2	0	133.1	104	33	37	12	25	3	0	0	525	1	8.10	1.69	4.80	0.81	22.9	4.8	0.97	.252	2.50	7.02
7	Roger Clemens R. Clemens	11	7	.611	29	28	3.70	137	1	1	0	158.0	136	65	67	15	57	4	1	1	665	9	7.80	3.25	2.40	0.85	20.6	8.6	1.22	.268	3.82	7.75
8	Greg Maddux G. Maddux	11	14	.440	35	30	3.27	125	2	0	1	198.0	195	72	97	14	51	9	2	16	836	4	5.68	2.32	2.45	0.64	15.0	6.1	1.24	.284	4.41	8.86
9	Chris Carpenter C. Carpenter	10	4	.714	18	18	3.00	68	1	1	0	108.0	104	36	43	11	36	6	0	2	461	1	5.67	3.00	1.89	0.92	14.8	7.8	1.30	.274	3.58	8.67
10	CC Sabathia	10	7	.588	26	23	4.28	121	1	0	0	130.1	137	62	67	15	63	8	0	9	586	5	8.36	4.35	1.92	1.04	20.6	10.8	1.53	.322	4.63	9.46
11	David Wells D. Wells	10	5	.667	27	17	3.17	83	1	0	0	125.0	116	44	49	12	25	7	2	2	508	1	5.98	1.80	3.32	0.86	16.3	4.9	1.13	.273	3.53	8.35
12	Jon Lester J. Lester	9	7	.563	26	22	2.51	133	0	0	0	154.0	117	43	46	15	40	3	2	0	610	4	7.77	2.34	3.33	0.88	21.8	6.6	1.02	.243	2.69	6.84
13	Orlando Hernandez O. Hernandez	9	3	.750	19	14	2.55	107	0	0	0	106.0	77	30	32	10	55	4	0	3	443	1	9.08	4.67	1.95	0.85	24.2	12.4	1.25	.251	2.72	6.54
14	Dave Stewart D. Stewart	9	3	.750	14	14	2.80	55	3	1	0	103.0	73	32	33	11	35	2	0	0	411	3	4.81	3.06	1.57	0.96	13.4	8.5	1.05	.201	2.88	6.38
15	Gerrit Cole G. Cole	8	4	.667	13	13	2.68	108	0	0	0	84.0	54	25	26	13	20	1	0	1	324	1	11.57	2.14	5.40	1.39	33.3	6.2	0.88	.225	2.79	5.79
16	Madison Bumgarner M. Bumgarner	8	3	.727	16	14	2.11	87	3	3	1	102.1	74	24	25	8	18	5	1	2	398	0	7.65	1.58	4.83	0.70	21.9	4.5	0.90	.236	2.20	6.51
17	John Lackey J. Lackey	8	6	.571	29	23	3.44	114	0	0	0	144.0	135	55	58	7	47	4	2	6	601	10	7.13	2.94	2.43	0.44	19.0	7.8	1.26	.298	3.63	8.44
18	Mariano Rivera M. Rivera	8	1	.889	96	0	0.70	110	0	0	42	141.0	86	11	13	2	21	3	78	4	527	3	7.02	1.34	5.24	0.13	20.9	4.0	0.76	.215	0.83	5.49
19	Charlie Morton C. Morton	7	3	.700	13	12	3.38	67	0	0	0	61.1	52	23	25	5	22	5	1	0	260	3	9.83	3.23	3.05	0.73	25.8	8.5	1.21	.292	3.67	7.63
20	Max Scherzer M. Scherzer	7	5	.583	22	18	3.38	137	0	0	0	112.0	81	42	45	12	46	7	0	3	463	5	11.01	3.70	2.98	0.96	29.6	9.9	1.13	.264	3.62	6.51
21	Cliff Lee C. Lee	7	3	.700	11	11	2.52	89	3	0	0	82.0	66	23	27	2	10	1	0	0	320	2	9.77	1.10	8.90	0.22	27.8	3.1	0.93	.294	2.96	7.24
22	Cole Hamels C. Hamels	7	6	.538	17	16	3.41	93	1	1	0	100.1	83	38	45	12	27	2	0	2	411	1	8.34	2.42	3.44	1.08	22.6	6.6	1.10	.256	4.04	7.45
23	Josh Beckett J. Beckett	7	3	.700	14	13	3.07	99	3	3	0	93.2	67	32	32	11	21	4	0	1	366	3	9.51	2.02	4.71	1.06	27.0	5.7	0.94	.242	3.07	6.44
24	Livan Hernandez L. Hernandez	7	3	.700	12	10	3.97	47	1	0	0	68.0	67	30	32	6	36	4	0	3	305	1	6.22	4.76	1.31	0.79	15.4	11.8	1.51	.288	4.24	8.87
25	Mike Mussina M. Mussina	7	8	.467	23	21	3.42	145	0	0	0	139.2	121	53	56	19	33	3	0	7	571	2	9.34	2.13	4.39	1.22	25.4	5.8	1.10	.275	3.61	7.80