Crasnick is surprisingly one of the more progressive baseball people on ESPN, as he regularly cites FanGraphs and defensive metrics in general when doing his list articles.
I liked his take, I think it is what most of us believe. We need scouting and metric data to estimate defense, and in the future we may have quantifiable answers to things like "What's the difference between line drives and fly balls?" How much we weigh each data set is what is currently in contention, I suppose.