The Knicks’ three young guards were struggling so badly against Portland Tuesday night that Jeff Hornacek said they were considering bringing in Jarrett Jack. But Hornacek is trying to stay committed to Emmanuel Mudiay, Frank Ntilikina and Trey Burke and let them play through their mistakes. They made plenty of them in the Knicks’ 111-87 loss, their 13th in the last 14 games. The three guards combined to shoot 5-for-28 with 13 points and seven turnovers, and they let Damian Lillard, C.J. McCollum and Shabazz Napier run circles around them. The three Portland guards totaled 68 points and were 15-for-21 on three-pointers. “It’s part of the development of these guys,” Hornacek said. “They’ve got to go through it. It’s tough. It’s tough on all of us. But when you hit that adversity and you’re not playing well how are you going to get yourself out of it? “It’s part of the experience that they unfortunately are going through right now.” Jack started 56 games, but coming out of the All-Star break the Knicks went all-in on playing the trio of young guards to let them develop and evaluate who has a long-term future with the team.