The Diamondbacks purchased Tonkin's contract Monday from the Long Island Ducks of the independent Atlantic League of Professional Baseball. He'll be assigned to Triple-A Reno.
Tonkin had previously spent time in the Rangers and Brewers organizations in 2019 before signing with Long Island in mid-June. The 29-year-old apparently made a positive impression on the Diamondbacks during his stint in independent ball and will be given a look in the Pacific Coast League as the season winds down. Tonkin has previously made 141 relief appearances at the big-league level, with his last MLB action coming in 2017.