Chapman is dealing with a cracked nail on his throwing hand, MLB.com reports.
Chapman (0-3) allowed three runs (one earned) on three hits and two walks across 0.2 innings to take the loss Sunday against the Cubs.
Chapman (0-2) allowed two earned runs on two hits and no walks while striking out one to take the loss Thursday against the Brewers.
Chapman's suspension has been reduced to one game, Andrew Destin of the Pittsburgh Post-Gazette reports.
Chapman was given a two-game suspension and fine Thursday for his actions versus the Mets on Monday, Jon Heyman of the New York Post reports.
Chapman signed a contract with Pittsburgh on Monday, Robert Murray of FanSided.com reports.
Chapman (6-5) blew a save and was tagged with Thursday's loss to Seattle. He allowed two runs on two hits and a walk without retiring a batter.
Chapman struck one over a scoreless inning in Wednesday's 5-0 win over the Angels.
Chapman picked up a save against the Mariners on Saturday, walking one batter and allowing no runs over two-thirds of an inning.
Chapman (6-4) struck out three over 1.2 innings to earn Tuesday's win over the Red Sox.