OAKLAND, Calif. - The Rangers juggled the rotation on Sunday, with Martin Perez and Andrew Cashner swapping spots.Perez moved up one day to start on Tuesday, on the normal four days rest if the series against Houston is played as scheduled. Perez is 4-0 with a 3.00 ERA for his last four starts on four days rest.Cashner would have six days rest for a start on Wednesday.