The Pirates placed Hayes on the 10-day injured list Monday with low-back inflammation, Noah Hiles of the Pittsburgh Post-Gazette reports.
It was reported earlier Monday that Hayes has been playing with a herniated disc in his back for much of the season, and this is the second time a back problem has landed him on the IL. It's not clear how much time he might miss. Jared Triolo figures to handle third base for now, although Isiah Kiner-Falefa could move there when Nick Gonzales (groin) returns.