best guess is your minutes or stamina settings, Your PF was exhausted most of the game and even hit DEEP RED at the end being very tired. He should of been off the floor 10 minutes earlier. Your gameplan looked fine but your players missed shots, could also be because of stamina and if they were tired or not although they appeared fine when given updates. Sometimes its just the luck of the draw, you also shot terrible from the FT line, 33 attempts with 63% is very no bueno.
It was a close loss and the teams are very balanced, you just had the bad draw. I'd look at past play by plays and see what your players look like at the end of the 1st and 2nd half and if you need to make adjustments to minutes/stamina settings.