The Celtics’ precise determination to keep their various veterans is difficult to calculate so soon after the defending champions’ Round 2 exit to the Knicks in six games and the devastating loss of Jayson Tatum to an Achilles rupture, but the early projections in circulation suggest Boston is more apt to make Jrue Holiday available via trade this offseason than Derrick White. Most rival teams continue to regard Kristaps Porziņģis as the most movable Boston vet thanks to the Latvian big man’s $30.7 million expiring contract. Porziņģis, though, managed to exceed 20 minutes in only one of the Celtics’ games in the New York series because of a perplexing energy-sapping illness that has plagued him since March.