Justin Verlander has lost the most career games by an active pitcher, with 158 games.

Interpreted as:

most active player regular-season losses

	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	ERA-	FIP	FIP-	H/9	PRAA
1	Justin Verlander J. Verlander	158	266	.373	555	.627	555	3.32	3,553	26	9	0	3567.2	3,046	1,317	1,428	371	1,004	121	0	28	14,607	99	8.96	2.53	3.54	0.94	24.3	6.9	1.14	.280	3.60	79	3.43	81	7.68	310.9
2	Patrick Corbin P. Corbin	142	110	.563	373	.437	354	4.51	1,860	7	2	2	2047.2	2,179	1,025	1,102	284	630	51	10	24	8,809	67	8.18	2.77	2.95	1.25	21.1	7.2	1.37	.317	4.84	107	4.13	99	9.58	9.7
3	Charlie Morton C. Morton	134	147	.477	416	.523	409	4.13	2,196	3	2	0	2267.2	2,143	1,040	1,139	226	859	200	1	27	9,755	72	8.72	3.41	2.56	0.90	22.5	8.8	1.32	.306	4.52	103	3.89	97	8.51	36.6
4	Kevin Gausman K. Gausman	113	112	.502	361	.498	322	3.81	1,954	4	2	0	1911.0	1,835	810	866	233	535	38	11	11	7,986	64	9.20	2.52	3.65	1.10	24.5	6.7	1.24	.307	4.08	92	3.59	85	8.64	132.7
5	Jose Quintana J. Quintana	110	113	.493	383	.507	357	3.76	1,816	2	2	0	2101.1	2,043	877	949	219	641	58	7	23	8,812	75	7.78	2.75	2.83	0.94	20.6	7.3	1.28	.300	4.06	91	3.76	90	8.75	91.5
6	Sonny Gray S. Gray	102	125	.449	339	.551	330	3.58	1,925	7	5	0	1918.0	1,675	763	836	192	621	57	2	5	7,952	106	9.03	2.91	3.10	0.90	24.2	7.8	1.20	.288	3.92	87	3.51	85	7.86	136.2
7	Wade Miley W. Miley	99	109	.476	320	.524	312	4.09	1,368	3	2	0	1757.1	1,783	798	855	198	611	46	3	10	7,519	58	7.01	3.13	2.24	1.01	18.2	8.1	1.36	.299	4.38	98	4.16	101	9.13	-6.3
8	Clayton Kershaw C. Kershaw	96	223	.301	455	.699	451	2.53	3,052	25	15	0	2855.1	2,193	804	881	235	713	46	1	28	11,279	108	9.62	2.25	4.28	0.74	27.1	6.3	1.02	.271	2.78	65	2.85	70	6.91	375.1
9	Yu Darvish Y. Darvish	93	115	.447	297	.553	297	3.65	2,075	2	1	0	1778.0	1,460	721	756	231	563	83	0	8	7,305	83	10.50	2.85	3.69	1.17	28.4	7.7	1.14	.282	3.83	87	3.58	85	7.39	120
10	Martín Pérez M. Pérez	93	91	.505	325	.495	279	4.41	1,153	4	3	0	1631.2	1,750	800	883	191	590	52	14	11	7,070	43	6.36	3.25	1.95	1.05	16.3	8.3	1.43	.307	4.87	100	4.44	103	9.65	-24.3
11	Kyle Hendricks K. Hendricks	91	105	.464	307	.536	301	3.79	1,373	6	4	0	1745.0	1,668	734	788	209	407	69	4	19	7,213	12	7.08	2.10	3.37	1.08	19.0	5.6	1.19	.283	4.06	92	3.96	96	8.60	34.9
12	Kyle Freeland K. Freeland	90	64	.584	236	.416	231	4.54	944	0	0	0	1260.1	1,394	636	690	180	392	47	0	12	5,466	17	6.74	2.80	2.41	1.29	17.3	7.2	1.42	.311	4.93	94	4.57	103	9.95	-17.5
13	Aaron Nola A. Nola	89	109	.449	285	.551	285	3.83	1,876	6	4	0	1715.2	1,522	730	769	217	449	56	0	16	7,039	18	9.84	2.36	4.18	1.14	26.7	6.4	1.15	.294	4.03	91	3.50	82	7.98	147.1
14	Chris Sale C. Sale	88	145	.378	393	.622	312	3.01	2,579	16	3	12	2084.0	1,692	697	750	213	487	130	25	15	8,389	48	11.14	2.10	5.30	0.92	30.7	5.8	1.05	.297	3.24	70	2.87	68	7.31	303.3
15	Luis Castillo L. Castillo	84	83	.503	243	.497	243	3.55	1,493	1	0	0	1410.2	1,208	557	608	174	453	48	0	8	5,824	19	9.53	2.89	3.30	1.11	25.6	7.8	1.18	.283	3.88	86	3.72	88	7.71	78.1
16	Nathan Eovaldi N. Eovaldi	84	102	.452	316	.548	297	3.89	1,487	5	3	0	1702.1	1,661	736	780	188	466	55	5	17	7,124	54	7.86	2.46	3.19	0.99	20.9	6.5	1.25	.299	4.12	95	3.75	92	8.78	66.2
17	José Berríos J. Berríos	82	108	.432	275	.568	273	4.08	1,481	5	1	0	1571.2	1,474	713	765	219	473	98	0	7	6,607	35	8.48	2.71	3.13	1.25	22.4	7.2	1.24	.289	4.38	97	4.18	99	8.44	14.3
18	Robbie Ray R. Ray	81	88	.479	265	.521	261	3.94	1,734	2	1	0	1441.0	1,250	631	674	216	608	51	1	19	6,097	60	10.83	3.80	2.85	1.35	28.4	10.0	1.29	.296	4.21	94	4.06	99	7.81	5.1
19	Gerrit Cole G. Cole	80	153	.343	317	.657	317	3.18	2,251	8	5	0	1954.0	1,627	690	740	217	500	61	0	8	7,861	58	10.37	2.30	4.50	1.00	28.6	6.4	1.09	.292	3.41	79	3.16	77	7.49	213.5
20	José Ureña J. Ureña	78	44	.639	251	.361	158	4.75	669	1	0	6	1003.1	1,032	530	568	137	377	52	36	26	4,355	25	6.00	3.38	1.77	1.23	15.4	8.7	1.40	.287	5.10	115	4.88	118	9.26	-84.3
21	Matthew Boyd M. Boyd	77	60	.562	213	.438	199	4.57	1,045	2	1	0	1088.0	1,053	553	589	176	336	53	2	7	4,614	32	8.64	2.78	3.11	1.46	22.6	7.3	1.28	.292	4.87	106	4.42	103	8.71	-14.8
22	Nick Pivetta N. Pivetta	76	69	.524	254	.476	209	4.47	1,329	2	0	3	1211.0	1,107	602	631	197	427	34	13	7	5,107	53	9.88	3.17	3.11	1.46	26.0	8.4	1.27	.292	4.69	105	4.22	100	8.23	1.1
23	Alex Cobb A. Cobb	76	78	.494	233	.506	233	3.84	1,108	6	2	0	1327.2	1,307	566	620	140	383	47	0	15	5,577	51	7.51	2.60	2.89	0.95	19.9	6.9	1.27	.299	4.20	94	3.81	92	8.86	43.8
24	Michael Wacha M. Wacha	75	110	.405	309	.595	288	3.89	1,416	2	2	0	1627.1	1,571	703	746	194	503	42	4	18	6,846	43	7.83	2.78	2.82	1.07	20.7	7.3	1.27	.294	4.13	96	3.96	97	8.69	17.3
25	Zack Wheeler Z. Wheeler	75	113	.399	283	.601	283	3.28	1,820	5	3	0	1728.1	1,475	630	683	166	490	76	0	14	7,086	41	9.48	2.55	3.71	0.86	25.7	6.9	1.14	.289	3.56	82	3.28	80	7.68	164.6