Between the 2002 and 2020 seasons, Clayton Kershaw had the most losses in the postseason, with 12 games.

Interpreted as:

most playoff losses by a player 2002 to 2020

	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	Clayton Kershaw C. Kershaw	12	13	.480	37	.520	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
2	Justin Verlander J. Verlander	11	14	.440	31	.560	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
3	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
4	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
5	CC Sabathia	7	9	.438	25	.563	22	4.34	116	1	0	0	124.1	131	60	65	15	58	8	0	8	558	5	8.40	4.20	2.00	1.09	20.8	10.4	1.52	.321	4.71	9.48
6	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
7	Zack Greinke Z. Greinke	6	4	.600	19	.400	19	4.22	96	0	0	0	106.2	96	50	53	18	30	3	0	0	440	2	8.10	2.53	3.20	1.52	21.8	6.8	1.18	.266	4.47	8.10
8	C.J. Wilson	6	1	.857	11	.143	10	5.26	44	0	0	0	53.0	49	31	35	10	30	4	0	6	237	3	7.47	5.09	1.47	1.70	18.6	12.7	1.49	.262	5.94	8.32
9	James Shields J. Shields	6	3	.667	11	.333	11	5.46	45	0	0	0	59.1	76	36	37	8	15	6	0	0	269	6	6.83	2.28	3.00	1.21	16.7	5.6	1.53	.349	5.61	11.53
10	Cole Hamels C. Hamels	6	7	.462	17	.538	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
11	Derek Lowe D. Lowe	6	4	.600	18	.400	12	3.56	54	0	0	1	78.1	66	31	34	10	28	2	4	5	328	1	6.20	3.22	1.93	1.15	16.5	8.5	1.20	.239	3.91	7.58
12	John Lackey J. Lackey	6	8	.429	29	.571	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
13	Mike Mussina M. Mussina	6	3	.667	13	.333	11	4.19	71	0	0	0	73.0	76	34	34	9	16	1	0	4	308	1	8.75	1.97	4.44	1.11	23.1	5.2	1.26	.318	4.19	9.37
14	Tyler Glasnow T. Glasnow	5	2	.714	8	.286	8	6.56	48	0	0	0	35.2	35	26	26	10	20	0	0	0	159	6	12.11	5.05	2.40	2.52	30.2	12.6	1.54	.309	6.56	8.83
15	Yu Darvish Y. Darvish	5	2	.714	7	.286	7	5.18	31	0	0	0	33.0	32	19	21	9	6	4	0	1	140	0	8.45	1.64	5.17	2.45	22.1	4.3	1.15	.256	5.73	8.73
16	Max Scherzer M. Scherzer	5	7	.417	22	.583	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
17	Adam Wainwright A. Wainwright	5	4	.556	28	.444	15	2.89	118	1	0	4	109.0	101	35	38	10	20	2	9	1	443	4	9.74	1.65	5.90	0.83	26.6	4.5	1.11	.311	3.14	8.34
18	Jake Peavy J. Peavy	5	1	.833	9	.167	9	7.98	21	0	0	0	38.1	53	34	34	4	17	0	0	4	178	1	4.93	3.99	1.24	0.94	11.8	9.6	1.83	.360	7.98	12.44
19	Tim Wakefield T. Wakefield	5	3	.625	12	.375	7	6.55	38	0	0	0	45.1	43	33	35	8	22	7	2	2	205	0	7.54	4.37	1.73	1.59	18.5	10.7	1.43	.269	6.95	8.54
20	Kyle Lohse K. Lohse	5	2	.714	13	.286	8	4.86	39	0	0	0	46.1	49	25	26	8	13	1	3	1	199	1	7.58	2.53	3.00	1.55	19.6	6.5	1.34	.297	5.05	9.52
21	Matt Morris M. Morris	5	2	.714	9	.286	9	4.96	30	0	0	0	52.2	57	29	31	8	26	5	0	3	240	2	5.13	4.44	1.15	1.37	12.5	10.8	1.58	.287	5.30	9.74
22	Trevor Bauer T. Bauer	4	1	.800	11	.200	7	2.94	44	0	0	0	33.2	33	11	16	4	8	1	1	1	143	1	11.76	2.14	5.50	1.07	30.8	5.6	1.22	.337	4.28	8.82
23	Kyle Hendricks K. Hendricks	4	2	.667	12	.333	11	3.12	51	0	0	0	57.2	53	20	22	10	16	3	0	1	242	0	7.96	2.50	3.19	1.56	21.1	6.6	1.20	.265	3.43	8.27
24	Masahiro Tanaka M. Tanaka	4	5	.444	10	.556	10	3.33	44	0	0	0	54.0	38	20	21	6	15	1	0	0	212	2	7.33	2.50	2.93	1.00	20.8	7.1	0.98	.219	3.50	6.33
25	Gerrit Cole G. Cole	4	8	.333	13	.667	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