Valencia scorched a Luke Gregerson offering to left field, driving in Josh Phegley and igniting the A's to a series-clinching, 5-4 walk-off win over the first-place Astros.
"We got a gift-wrapped present from Toronto, I promise you that," A's starter Chris Bassitt said. "My goodness. How he got [designated for assignment] is shocking to every single person on this team, including coaches. I don't know how we got him. I really don't. He is unreal."
Valencia, who also homered in the fourth, finished the series 6-for-11 with two home runs, five RBIs and the walkoff.