Koschak tossed a three-hitter and overcame five error by his teammates, and Ely pushed across two runs in the bottom of the sixth to edge Chisholm 5-3 at Veterans Memorial Field.
Consecutive two-out hits by Sean Fisher and Josh Ojala gave Ely the lead, and Koschak, who did not give up an earned run, retired Chisholm (10-6) in the seventh.
Koschak picked up his third win of the year while striking out six, and Ely improved to 18-5 overall.
Losing pitcher Tony Clement stymied Ely for most of the night, althoguh the hosts scored once in the first and got two unearned runs in the third. Fisher walked and scored in the opening frame, and the leadoff man reached on an error to start the third. He scored on the back end of a double steal, and Koschak's two-out double brought in Ojala to make it 3-2.
Two Ely errors allowed Chisholm to tie the game in the top of the sixth, but the winners came back in the bottom of the frame. Jory Johnson walked to start the rally, and after a bunt and a strikeout, Fisher came through with a bloop single to right. Fisher later stole second and scored on Ojala's second hit of the night.
Koschak worked through the Ely fielding miscues and stranded eight Chisholm runners in the game.