The move was made before Monday night's game against the Baltimore Orioles.
Napoli was put on the 15-day DL on June 12 with a strained left oblique muscle. He had been bothered by the injury to his side for several days before he irritated it June 11 in a game at Minnesota.
Napoli hit .221 with 10 homers and 25 RBI in 46 games for Texas this season. He hit three homers during four games on a rehab assignment in Round Rock. He had a game-ending, three-run homer Sunday night.
Teagarden has hit .269 over nine games and three stints with Texas this season.