Switch to Brummbär + Paks + Grens.
Might I add Puma + Brummbar + Panther is a pretty solid combo. Panther can take hits and screen the Brummbar that keeps inf away while Puma can flank and hunt down mediums. StuGG is also a good alternative to the Panther vs mediums spam.
Puma has been surprisingly great despite the late deployment around 10mins.