The Diamondbacks optioned Tawa to Triple-A Reno on Monday, John Gambadoro of Arizona Sports 98.7 FM reports.
Tawa has been on the Arizona roster all season but hasn't played much, particularly in May with only four starts and 19 plate appearances. He's clearing out to make space on the roster for Pavin Smith (elbow), who is back from the 60-day injured list.