Beavers Dam Cubs 6-2
Chang, batting out of the eighth spot in the lineup, smacked a two-run homer, his first, in the second inning and ripped an RBI single in the fourth for the Beavers (24-27).
Portland starter Mike Thompson (1-5) snapped a personal five-game losing streak after giving up two runs -- one earned -- on eight hits and three walks with four strikeouts in a season-high seven innings. He lowered his ERA to 9.73.
The right-hander escaped two bases-loaded jams with a pair of 1-2-3 double plays.
Cubs starter John Webb (1-1) allowed four runs on seven hits and three walks with two strikeouts in five innings. Reliever Ben Howard gave up a run-scoring triple to Adam Shabala and a sacrifice fly to Josh Howard in the eighth.
Geovany Soto went 2-for-4 with an RBI for Iowa (29-22) to extend his hitting streak to 11 games.