How the hell do you get out-attritioned by 4 shermans with 2 panthers, brn?
You need to do something seriously wrong for that to happen.
Call on a sherman... kill some stuff, Panther comes out in response. Dispatch it with Sherman + ATG (even still should you lose the sherman you have another to bring out easily)
When Panther is dead use another Sherman, force his hand into calling out the other panther. Repeat step +ATG. Panthers dead. Call out remaining shermans.