John Costello ERA in 1990

• John Costello's highest ERA of the 4 seasons on file; the best is 1.81 in 1988.
• Up 2.59 from 3.32 in 1989.

Best of 4 regular seasons, 1988 through 1991. Figures come from ESPN's box scores and were last read on September 23, 2026.

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John Costello ERA in 1990, 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.
1988	STL	36	5	2	1.81	49.2	38	25	1.39	1
1989	STL	48	5	4	3.32	62.1	40	20	1.09	3
1990	STL/WSH	8	0	0	5.91	10.2	2	2	1.31	0
1991	SD	27	1	0	3.09	35.0	24	17	1.54	0

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