The visitors sat in and put men behind the ball, putting the onus on Northampton to force the issue, something they struggled to do, especially in the first-half.
Tom Nichols scored with one of Crawley's three shots while the Cobblers failed to convert any of their 17 attempts.
"The way Crawley had been playing before, they were playing quite high so that was something we worked on in training - how to get in behind them," revealed Mitch Pinnock.
"But in the game on Saturday, they sat on the edge of their box and we didn't expect it to be honest and that's probably why it took us a bit of time to work out how to play against it.
"It's difficult to find space but that's why we need to come up with a plan B. They obviously did their homework on us and dealt with the balls we put in the box.
"We needed to be a bit more creative to create a few more opportunities in the first-half but we did that in the second and to be honest I just felt we were unlucky."
Cobblers did improve and dominated the final half-hour, creating and missing a series of clear opportunities.
Pinnock added: "We weren't ourselves in the first-half but I thought we created loads of chances in the second and we really should have got a goal.
"We needed to show more composure because the chances were there for us. I felt that, had we got one goal, we would have gone on and won the game, but it didn't seem to fall for us.
"But there were promising signs because we were on top and that's something we want to carry into this week."