Walton was TSN Minor League Player of the Year in 1969 when he hit .332 and led the American Association with 25 HR and 119 RBI; that August 31 the Astros traded him with Sandy Valdespino to the Seattle Pilots for Tommy Davis. In the first half of 1970, Walton was among the AL leaders in HR and RBI, but he was slowed down by a knee operation in the latter part of the season. He finished with a .257 batting average, 17 HR, and 66 RBI in 397 at-bats, but struck out 126 times. He was never again a regular. He tried Japanese baseball in 1978 but hit .215 for Taiyo.