I think that losing Calathes gave one important thing to our team: a hungry, defensive identity. We would not have the same identity with Calathes (we'd probably also have a more consistent half court offense...)
As far as Chandler Parsons, he finally bought into the coaching staff, and something clicked for him to work harder. The gym, practices, etc. probably helped him put it all together, but it's not so much as playing in Calathes' shadow.
However, if you believe- as I do- that Calathes as a team leader (simply by being the best player on our team) stunted our team's defensive identity, you'd have to think that any negative influence of Calathes would be presented more in Parsons, due to their background together. Factor in suspected riffs between Calathes and the coaches, and I'm not sure Parsons would have had the same motivation to work hard and start realizing his five-star potential with Calathes here.
So I guess I do agree to an extent that Parsons' (and the teams'

development can be attributed to Calathes' early departure, but I think for a different reason than the more common theory.