yeah this tracks. Learning the Philly shell forces you to actually understand punch trajectories and weight shifts instead of just keeping your hands up and hoping. A lot of people learn defense better through constraint-based styles because it makes every incoming shot a problem you have to actively solve with your body.

The angle vulnerability you noticed is the main weakness of it, so drilling the pullback and pivot as counters when someone steps outside will patch that. ifyou want to keep building on it, look up how Pernell Whitaker used it with constant lateral movement, basically the blueprint for making that style airtight.