With the loss, West Michigan falls to 73-33 on the year and 28-11 in the second half. West Michigan leads Fort Wayne by three games for first place in the Midwest League Eastern Division second half standings.
Austin Athmann was the lone Whitecap with more than one hit, finishing with two while Chad Sedio finished with two RBIs.
Starting pitcher Anthony Castro took the loss, surrendering six earned runs on nine hits in 4 1/3 innings while walking four.
West Michigan will next travel to Lake County on Saturday to begin a five game series beginning at 7 p.m.