"You get away from small samples and you allow itself to play out and allow both guys to give you enough information to make that decision," Porter said.
Presley, who was hitting .455 during his seven-game streak, is a left-handed hitter who has been starting in left field against right-handers. With lefty Tommy Milone on the mound Sunday for the A's, L.J. Hoes got the start in left field.
Meanwhile, Castro, who also hits left-handed, was out of the lineup in favor of the switch-hitting Corporan. It's fair to point out that Castro had caught seven games in a row and 10 of the last 11 for the Astros, who are off on Monday.
"Had a righty been on the mound today [for Oakland], Castro would have played and he would have gotten just one off-day," Porter said. "Looking at the workload and number of innings in which he's caught consecutive, I felt it was a good time to take advantage and get his legs underneath him and take two days off."
Brian McTaggart is reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.