Jerry Koosman career ERA

• Best season on file: 2.08 in 1968.
• Most recent: 4.62 in 1985.

Average of 19 regular seasons, 1967 through 1985. Figures come from ESPN's box scores and were last read on September 22, 2026.

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Jerry Koosman career ERA, season by season

Season↓	Team↓	GP↓iGP: Games the player appeared in, however briefly.	W↓iW: Games in which this pitcher was credited with the win.	L↓iL: Games in which this pitcher was charged with the loss.	ERA↓iERA: Earned runs allowed per nine innings pitched — lower is better. Under 3.00 is excellent.	IP↓iIP: Innings pitched. The decimal counts outs, so 6.2 is six innings and two more outs.	K↓iK: Batters this pitcher struck out.	BB↓iBB: Times the batter reached first base on four balls.	WHIP↓iWHIP: Walks and hits allowed per inning pitched — lower is better. Around 1.00 is elite.	SV↓iSV: Games finished by protecting a narrow lead to the last out.
1967	NYM	9	0	2	6.04	22.1	11	19	1.84	0
1968	NYM	35	19	12	2.08	263.2	178	69	1.10	0
1969	NYM	32	17	9	2.28	241.0	180	68	1.06	0
1970	NYM	30	12	7	3.14	212.0	118	71	1.23	0
1971	NYM	26	6	11	3.04	165.2	96	51	1.27	0
1972	NYM	34	11	12	4.14	163.0	147	52	1.27	1
1973	NYM	35	14	15	2.84	263.0	156	76	1.18	0
1974	NYM	35	15	11	3.36	265.0	188	85	1.29	0
1975	NYM	36	14	13	3.42	239.2	173	98	1.39	2
1976	NYM	34	21	10	2.69	247.1	200	66	1.10	0
1977	NYM	32	8	20	3.49	226.2	192	81	1.22	0
1978	NYM	38	3	15	3.75	235.1	160	84	1.30	2
1979	MIN	37	20	13	3.38	263.2	157	83	1.33	0
1980	MIN	38	16	13	4.03	243.1	149	69	1.32	2
1981	MIN/CHW	27	4	13	4.01	121.1	76	41	1.37	5
1982	CHW	42	11	7	3.84	173.1	88	38	1.34	3
1983	CHW	37	11	7	4.77	169.2	90	53	1.35	2
1984	PHI	36	14	15	3.25	224.0	137	60	1.30	0
1985	PHI	19	6	4	4.62	99.1	60	34	1.42	0

What the columns mean: W · L · ERA · IP · K · BB · WHIP · SV