The Cobblers, beaten League Two play-off finalists at Wembley in May, have lost three of their opening four league and cup matches this term, finishing with 10 men on two occasions.
And Boothroyd wants to see his side wise up ahead of Torquay's visit to Sixfields this weekend.
"We have had two players sent off in our first three league games and that has clearly made our job harder," he told the club's official website. "It clearly doesn't help us but we were naive at Southend (a 2-0 defeat last Saturday) and our enthusiasm got the better of us.
"We also let the game get the better of us and we allowed ourselves to be influenced by the surroundings rather than be professional. We are a new team and these are lessons, we will learn from them and improve but we need to manage games and situations better than we have so far.
"Every player selected for us has a responsibility to not just play their own game but to help manage the game. You can't just let things develop, you need to control the game and the surroundings and we must learn to do that. Giving away silly cards and silly free-kicks just invites pressure and it has to stop."
Hackett managed 75 minutes while Platt featured for just under an hour as goals from JJ Hooper and Ishmel Demontagnac secured the triumph.
Hackett, however, will miss Saturday's clash against Torquay as he serves a one-match suspension following his dismissal at Roots Hall.