Spurs may be angry over Marcus Morris, but sources explain how bad blood could go back to Kristaps PorzingisBoth teams feel lines were crossed in different situations7/19/2019, 3:07 PMJan 31, 2018; Boston, MA, USA; New York Knicks forward Kristaps Porzingis (6) shoots over Boston Celtics forward Marcus Morris (13) during the second quarter at TD Garden. Mandatory Credit: Winslow Townson-USA TODAY Sports / Winslow Townson