Bart, the No. 2 overall pick in the 2008 draft, is hitting just .156 and has an OPS of .596 with 49 strikeouts in 108 plate appearances in his first chance to take over for former MVP and seven-time All-Star Buster Posey, who retired after last season. Bart has hit four home runs this season with seven RBIs.
"We still think Joey is an everyday catcher," Giants president of baseball operations Farhan Zaidi told reporters, according to the San Francisco Chronicle. "In the broader scheme of things, we thought it made sense to get him a little bit of a reset. We're very open to the notion that at-bats at Triple-A out of the spotlight can help get a guy on track."
Bart, 25, spent most of last season at Triple-A where hit .294 with an OPS of .831 in 279 plate appearances for Sacramento in 2021. But he has just a .201 average and an OPS of .605 in 225 career plate appearance at the major league level.
Wynns, 31, was hitting .365 with an OPS of 1.004 in 134 plate appearances this season for Lehigh Valley, the Phillies' Triple-A affiliate. He has 115 games at the major league level, for the Baltimore Orioles, hitting .216 with an OPS of .580. He has nine home runs in his major league career.
The Giants sent left-hander Michael Plassmeyer and cash considerations to the Phillies for Wynns.