Rajon Rondo’s maturation regularly warrants discussion in Boston, largely due to his prickly reputation but also because his leadership will become more and more important as the Celtics continue their transition to the post-Big Three era. This summer we have evidence that Rondo’s leadership skills are developing. On a team with several highly-regarded veterans in their mid-30s, it was Rondo that organized team activities at UCLA in preparation for training camp. “Rondo has been great, just terrific this summer,” Rivers told ESPN Boston. “He reached out to all the players and got every single one of them to fly to L.A. and practice together. They put in about four or five hours a day. Paul and KG were already out there, but Rondo got Jason and Courtney Lee and all the other guys on board too.