After talking to a Pro, my best guess as to my large losses this year where late repotting and the white fleshy roots were unable to keep up with with the transpiration needs of the increased needle mass. Maybe this didn’t bite me in previous years since the trees had less needle mass (although it seems like the root to needle mass would have been similar). I probably kept them too dry after the repot, since I was worried about overwatering. It didn’t help that we had some dry, windy Santa Ana days after the repots.