It gives you more information about the health of the canopy of the tree. In this particular case, it gave us more information about the health of the cavity within the tree.
Viewing the tree only from the ground is considered a limitation in terms of an assessment. Last week we were able to get a piece of equipment that brought a staff member up into the canopy to collect the twigs. Looking at the length of those twigs, and the health of the buds across the different parts of the tree does give you a good idea of the health of the tree in terms of how much growth it was able to sustain last year. That's not isolated just to the most recent period; that's the entire year's growth.
It's very important to get a close-up look at the cavity as well. It gives you an idea of whether the tree is successfully containing the decay agent for whatever caused that hollowing.