After Cedar Rapids scored three runs in the top of the sixth, West Michigan responded with three runs of their own in the seventh inning.
The Whitecaps seventh inning runs came via a Wenceel Perez single that scored McMillan and an Ulrich Bojarski singled that scored Tuck and Perez.
The Whitecaps surrendered two runs in the eighth inning which ultimately made the final score 8-4.
Tuck has two hits and one run while Bojarski had one hits and two RBIs.
With the loss, the Whitecaps fall to 14-18 overall on the season and are now five games behind Great Lakes and Lake County for first place in the Midwest League Eastern Division.
The Whitecaps will continue their series at home against Cedar Rapids on Friday, with first pitch scheduled for 7:05 p.m.