The bad blood between the New York Knicks and the San Antonio Spurs following the Marcus Morris situation could be traced back to how the Spurs dealt with Kristaps Porizingis when he was still on the Knicks, league sources told Ian Begley of SNY.

The Knicks, who discussed trading Porzingis prior to the 2017 NBA Draft, felt as if the Spurs "operated outside of accepted NBA norms" prior to Porzingis getting traded to the Mavs, according to SNY. 

It is unclear what exactly the Spurs did to make the Knicks feel like a line was crossed.

The Spurs were reportedly "pissed" about Morris backing out of an agreement with the team to sign a one-year deal with the Knicks, a general manager told Frank Isola of The Athletic