Like @Work=wins and @BigSkyHi alluded to, it doesn't look like she is loading the upper half (counterotation) as well in the backyard swings BUT that may be because the cage swings look to be against much lower velocity than the backyard swings and in the backyard swings she may not be giving herself enough time. Do you have game swings from when she was hitting well in games and also right now? If you don't get started early enough (for your movement pattern) that can screw up everything..
I think this hitter has a ‘sway’. Which kills balance and the first stretching point.. so no resistance for separation to occur on time. Subsequently the cage swing has separation, no sway as well. Not perfect but better.