Tom Glavine has the most career losses in the postseason, with 16 games.

Interpreted as:

most career losses by a player in postseason

	NAME	L	W	L%	G	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%	WHIP	BABIP	RA	H/9
1	Tom Glavine T. Glavine	16	14	.533	35	.467	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
2	Greg Maddux G. Maddux	14	11	.560	35	.440	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
3	Clayton Kershaw C. Kershaw	13	13	.500	40	.500	32	4.63	213	0	0	1	196.1	171	101	107	32	54	4	2	6	802	11	9.76	2.48	3.94	1.47	26.6	6.7	1.15	.279	4.90	7.84
4	Justin Verlander J. Verlander	12	17	.414	38	.586	37	3.58	244	2	1	0	226.0	179	90	93	32	74	5	0	0	920	8	9.72	2.95	3.30	1.27	26.5	8.0	1.12	.260	3.70	7.13
5	Andy Pettitte A. Pettitte	11	19	.367	44	.633	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
6	David Price D. Price	9	5	.643	23	.357	14	4.62	91	0	0	1	99.1	91	51	53	16	28	3	5	1	414	1	8.24	2.54	3.25	1.45	22.0	6.8	1.20	.272	4.80	8.24
7	Randy Johnson R. Johnson	9	7	.563	19	.438	16	3.50	132	3	2	0	121.0	106	47	51	15	32	0	2	2	493	0	9.82	2.38	4.13	1.12	26.8	6.5	1.14	.290	3.79	7.88
8	Yu Darvish Y. Darvish	8	5	.615	14	.385	14	3.96	62	0	0	0	72.2	62	32	34	18	15	8	0	1	296	1	7.68	1.86	4.13	2.23	20.9	5.1	1.06	.228	4.21	7.68
9	Max Scherzer M. Scherzer	8	7	.533	30	.467	25	3.78	171	0	0	1	143.0	109	60	63	20	56	9	1	4	594	8	10.76	3.52	3.05	1.26	28.8	9.4	1.15	.263	3.97	6.86
10	Mike Mussina M. Mussina	8	7	.533	23	.467	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
11	Roger Clemens R. Clemens	8	12	.400	35	.600	34	3.75	173	1	1	0	199.0	173	83	87	17	70	6	1	1	837	10	7.82	3.17	2.47	0.77	20.7	8.4	1.22	.273	3.93	7.82
12	Jerry Reuss J. Reuss	8	2	.800	11	.200	11	3.59	25	2	1	0	62.2	57	25	30	5	25	0	0	3	271	1	3.59	3.59	1.00	0.72	9.2	9.2	1.31	.241	4.31	8.19
13	Whitey Ford W. Ford	8	10	.444	22	.556	22	2.71	94	7	3	0	146.0	132	44	51	8	34	3	0	2	594	4	5.79	2.10	2.76	0.49	15.8	5.7	1.14	.273	3.14	8.14
14	Jon Lester J. Lester	7	9	.438	26	.563	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
15	CC Sabathia	7	10	.412	26	.588	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
16	Derek Lowe D. Lowe	7	5	.583	26	.417	12	3.42	70	0	0	1	97.1	81	37	45	12	32	4	4	6	408	1	6.47	2.96	2.19	1.11	17.2	7.8	1.16	.238	4.16	7.49
17	Tim Wakefield T. Wakefield	7	5	.583	18	.417	11	6.75	54	2	0	0	72.0	68	54	56	13	38	9	2	2	329	1	6.75	4.75	1.42	1.63	16.4	11.6	1.47	.256	7.00	8.50
18	Charlie Leibrandt C. Leibrandt	7	1	.875	13	.125	7	3.77	34	1	0	0	57.1	53	24	25	2	19	2	2	1	238	0	5.34	2.98	1.79	0.31	14.3	8.0	1.26	.282	3.92	8.32
19	Framber Valdez F. Valdez	6	7	.462	17	.538	16	4.34	95	0	0	0	85.0	82	41	45	14	34	4	1	0	360	0	10.06	3.60	2.79	1.48	26.4	9.4	1.36	.319	4.76	8.68
20	Jack Flaherty J. Flaherty	6	2	.750	12	.250	11	5.24	56	0	0	0	55.0	56	32	33	9	23	2	0	0	240	3	9.16	3.76	2.43	1.47	23.3	9.6	1.44	.313	5.40	9.16
21	Tyler Glasnow T. Glasnow	6	2	.750	11	.250	10	5.51	63	0	0	0	47.1	45	29	30	10	27	0	0	0	212	7	11.98	5.13	2.33	1.90	29.7	12.7	1.52	.313	5.70	8.56
22	Max Fried M. Fried	6	2	.750	22	.250	14	5.31	73	0	0	0	76.1	94	45	47	11	23	2	0	0	343	4	8.61	2.71	3.17	1.30	21.3	6.7	1.53	.355	5.54	11.08
23	Gerrit Cole G. Cole	6	11	.353	22	.647	22	2.77	156	0	0	0	133.1	100	41	50	19	36	3	0	1	537	1	10.53	2.43	4.33	1.28	29.1	6.7	1.02	.251	3.38	6.75
24	Anibal Sanchez A. Sanchez	6	3	.667	11	.333	10	2.93	64	0	0	0	61.1	51	20	22	9	19	2	0	1	256	4	9.39	2.79	3.37	1.32	25.0	7.4	1.14	.259	3.23	7.48
25	Zack Greinke Z. Greinke	6	4	.600	22	.400	21	4.14	100	0	0	0	113.0	103	52	55	19	33	3	0	0	469	2	7.96	2.63	3.03	1.51	21.3	7.0	1.20	.268	4.38	8.20