The move was retroactive to Monday, a day after Smith allowed an RBI double to San Diego's Eric Hosmer in the sixth inning. Smith got the win when the Mets rallied in the bottom half.
A right-hander in his fourth big league season with the Mets, Smith is 2-3 with a 3.51 ERA in 37 relief appearances.
Smith, 28, had a 1.99 ERA in 29 appearances through June 24 but has an 8.68 ERA since while allowing runs in six of eight games. He has given up four home runs in those eight games, raising his season total to eight in 41 innings.