"I thought it was a terrific start and I thought we got gradually worse," Boothroyd said after the 2-1 win against the Sky Blues at Vicarage Road.
"We allowed them back into the game and then it was about grinding out a result and we managed to do that.
"For me, it was important that we did get the win today and I said to the players at the end 'well done on the win, but we all know that's not good enough for us, for what we've come to expect'.
"But it's a very strange game where you can play really well for a run of games and end up drawing and then you don't play particularly well for the whole of the 90 and you end up with a win."