The TinCaps started off well, leading 3-0 after three innings with starter Bryan Verbitsky cruising in his team debut.
They never scored again, allowed two runs in the fourth and four in the sixth and dropped the opener of a four-game series with Great Lakes, 7-3.
Verbitsky went five innings and gave up two runs on five hits with six strikeouts.
Justin Livengood faced eight batters and four scored. He took the loss.
Victor Arano earned his second win of the season, going five innings and giving up three runs on four hits with six strikeouts.
Jake Bauers had a two-run triple in the second and scored on an RBI groundout by Jose Carlos Urena.
The TinCaps (9-14) had only two hits the rest of the way.
The Loons (14-10) went ahead on a three-run triple by Dillon Moyer.
The TinCaps lost three out of four at Great Lakes last week and had hoped being at home would produce better results.