The 22-year old Argentine midfielder, who recently joined from River Plate, made a 30-minute cameo for his new club and Hyndman was instantly pleased.
"What I wanted to do was play him along with David [Ferreira] and more of the regular starters," Hyndman told reporters after the match.
"That way, we could have a chance to see more of his playmaking, his vision. I think he's the player we were all anticipating."
And Diaz was also content with how his first real showing for the Texan club panned out.
"I feel that I had a good connection with Ferreira and other players up front," he said through an interpreter. "There's an understanding that will improve in practice."