Olson collected his 10th home run in Tuesday's 8-2 loss to the host Angels, joining Chapman (10) and Pinder (12) in double-digit territory and giving the A's three rookies with 10 homers or more for just the second time in Oakland history.
The only other instance came in 1977, when Wayne Gross, Mitchell Page and Tony Armas teamed up to accomplish the feat.
"We're excited about this group, and they're getting a chance not only to play and get some regular at-bats, but they're getting to do it together, too," A's manager Bob Melvin said.