Cy Young played the most seasons with 15+ pitcher losses, with 12 seasons.

	NAME	SEAS	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	Cy Young C. Young	12	214	278	.435	540	.565	479	2.86	1,617	440	41	13	4321.2	4,350	1,374	2,010	83	734	90	56		17,537	94	3.37	1.53	2.20	0.17	9.2	4.2	1.18	.284	4.19	79	2.92	79	9.06	368.2
2	Jack Powell J. Powell	11	192	184	.511	429	.489	388	3.12	1,195	326	32	12	3303.2	3,313	1,146	1,566	101	767	89	39		13,570	53	3.26	2.09	1.56	0.28	8.8	5.7	1.23	.281	4.27	97	3.13	99	9.03	5.6
3	Pud Galvin P. Galvin	11	269	324	.454	614	.546	602	2.81	1,662	573	54	1	5289.2	5,615	1,650	2,882	105	579	29	15		22,277	205	2.83	0.99	2.87	0.18	7.5	2.6	1.17	.277	4.90	94	2.91	95	9.55	84.3
4	Gus Weyhing G. Weyhing	10	208	240	.464	477	.536	449	3.70	1,558	412	26	3	3901.0	3,978	1,604	2,429	99	1,387	251	27		17,128	233	3.59	3.20	1.12	0.23	9.1	8.1	1.38	.280	5.60	94	3.68	96	9.18	70.2
5	John Clarkson J. Clarkson	9	163	309	.345	492	.655	484	2.76	1,845	458	36	5	4243.2	3,979	1,303	2,180	143	1,118	80	8		17,888	164	3.91	2.37	1.65	0.30	10.3	6.3	1.20	.261	4.62	75	3.30	88	8.44	272
6	Robin Roberts R. Roberts	8	134	138	.493	328	.507	286	3.59	1,149	163	25	18	2266.2	2,223	904	978	251	408	25	34	30	9,268	13	4.56	1.62	2.82	1.00	12.4	4.4	1.16	.265	3.88	92	3.48	89	8.83	108.1
7	Bobo Newsom B. Newsom	8	143	110	.565	321	.435	276	4.19	1,182	151	18	14	2137.0	2,190	995	1,139	113	993	27	30		9,389	37	4.98	4.18	1.19	0.48	12.6	10.6	1.49	.294	4.80	98	3.84	91	9.22	86.5
8	Chick Fraser C. Fraser	8	164	108	.603	294	.397	271	3.97	767	247	10	3	2342.0	2,441	1,033	1,499	54	975	162	23		10,248	104	2.95	3.75	0.79	0.21	7.5	9.5	1.46	.288	5.76	115	3.92	112	9.38	-113.8
9	Tony Mullane T. Mullane	8	173	232	.427	430	.573	401	2.97	1,438	383	27	4	3607.2	3,324	1,189	1,964	65	979	95	30		15,335	271	3.59	2.44	1.47	0.16	9.4	6.4	1.19	.256	4.90	84	3.39	97	8.29	46.9
10	Mickey Welch M. Welch	8	164	214	.434	404	.566	400	2.71	1,323	384	29	0	3477.2	3,420	1,049	1,900	76	794	19	5		14,674	202	3.42	2.05	1.67	0.20	9.0	5.4	1.21	.268	4.92	92	3.16	104	8.85	-38
11	Bert Blyleven B. Blyleven	7	115	110	.511	260	.489	259	3.06	1,529	121	31	0	1970.1	1,841	671	751	131	479	70	1	23	8,077	38	6.98	2.19	3.19	0.60	18.9	5.9	1.18	.291	3.43	82	2.72	73	8.41	215.4
12	Bob Friend B. Friend	7	124	90	.579	274	.421	246	3.46	868	84	18	4	1756.0	1,796	676	787	126	428	25	16	66	7,383	32	4.45	2.19	2.03	0.65	11.8	5.8	1.27	.281	4.03	93	3.20	87	9.21	92.9
13	Murry Dickson M. Dickson	7	123	89	.580	313	.420	202	3.83	676	92	15	18	1702.1	1,763	725	833	191	564	16	74		7,258	12	3.57	2.98	1.20	1.01	9.3	7.8	1.37	.271	4.40	93	4.20	101	9.32	-4.6
14	Early Wynn E. Wynn	7	115	78	.596	236	.404	212	4.36	699	101	14	5	1513.0	1,609	733	828	114	588	25	21	16	6,595	16	4.16	3.50	1.19	0.68	10.6	8.9	1.45	.289	4.93	117	3.79	102	9.57	-14.6
15	Bullet Joe Bush B. Joe Bush	7	117	97	.547	249	.453	206	3.14	785	135	25	6	1709.2	1,619	597	754	31	741	33	34		7,189	60	4.13	3.90	1.06	0.16	10.9	10.3	1.38	.284	3.97	96	3.25	99	8.52	1.3
16	Walter Johnson W. Johnson	7	128	144	.471	305	.529	254	2.20	1,348	209	38	11	2274.1	1,876	556	737	29	556	74	46		8,953	68	5.33	2.20	2.42	0.11	15.1	6.2	1.07	.266	2.92	75	2.28	76	7.42	164.1
17	George Mullin G. Mullin	7	130	123	.514	281	.486	262	2.75	934	225	23	5	2224.0	2,089	679	990	20	776	72	17		9,201	53	3.78	3.14	1.20	0.08	10.2	8.4	1.29	.280	4.01	95	2.93	105	8.45	-28
18	Win Mercer W. Mercer	7	137	116	.542	288	.458	257	3.87	473	213	10	9	2119.0	2,630	912	1,499	54	652	128	30		9,488	38	2.01	2.77	0.73	0.23	5.0	6.9	1.55	.315	6.37	91	4.22	99	11.17	17.5
19	Pink Hawley P. Hawley	7	140	127	.524	304	.476	264	4.05	686	230	8	3	2333.0	2,589	1,050	1,515	49	779	168	35		10,256	66	2.65	3.01	0.88	0.19	6.7	7.6	1.44	.296	5.84	93	4.23	97	9.99	31.8
20	Kid Nichols K. Nichols	7	119	171	.410	310	.590	287	2.84	1,106	279	30	7	2588.2	2,472	817	1,244	83	670	70	22		10,788	103	3.85	2.33	1.65	0.29	10.3	6.2	1.21	.270	4.33	74	3.28	84	8.59	199
21	William Hutchinson W. Hutchinson	7	158	180	.467	368	.533	339	3.56	1,225	317	21	4	3022.1	3,055	1,196	1,861	99	1,109	84	28		13,196	120	3.65	3.30	1.10	0.29	9.3	8.4	1.38	.277	5.54	86	3.74	89	9.10	161
22	Mark Baldwin M. Baldwin	7	165	154	.517	346	.483	328	3.37	1,349	295	14	5	2802.1	2,695	1,050	1,816	81	1,307	123	19		12,470	221	4.33	4.20	1.03	0.26	10.8	10.5	1.43	.272	5.83	91	3.79	100	8.66	-0.9
23	Adonis Terry A. Terry	7	131	113	.537	267	.463	252	3.54	1,062	235	12	5	2181.1	2,147	859	1,390	44	667	47	15		9,426	151	4.38	2.75	1.59	0.18	11.3	7.1	1.29	.278	5.74	102	3.36	96	8.86	29
24	Tim Keefe T. Keefe	7	152	209	.421	373	.579	371	2.62	1,529	357	20	0	3206.0	2,855	935	1,550	43	648	24	3		13,232	149	4.29	1.82	2.36	0.12	11.6	4.9	1.09	.256	4.35	81	2.89	89	8.01	132.5
25	Jim Whitney J. Whitney	7	181	164	.525	360	.475	347	2.95	1,279	332	20	2	3050.1	3,159	1,000	1,786	62	354	25	12		12,798	194	3.77	1.04	3.61	0.18	10.0	2.8	1.15	.280	5.27	97	2.74	89	9.32	113.9