Evans spoke to the clubs official website and explained he was majorly disappointed to take nothing away from Sixfields.
He said: "We did not start the match well and deserved to go a goal down. A couple of the lads did not play to the game plan in the first 25 minutes and it knocked our team shape completely out. However, we managed to get those two lads focused and from then on till the end of the match we were by a country mile the better team.
''This was a much improved performance from the one we put in when we beat Burton Albion on Saturday. We passed the ball effectively; we had 23 efforts on there goal and hit the target 15 times so we must give credit to the home goalkeeper who had an inspired night.
''We have to take this defeat on the chin and learn plenty from it. I can say now we will play much worse and win matches whereas I cannot see Northampton getting battered like that for over an hour and winning, football really is a strange business at times."
Evans added: "I asked my lads to compete with Northampton physically and to a man we done that. Everyone in the ground last night knows we should have won the match but it went against us and we need to put it behind us.
''We must now turn our sole focus to Chesterfield on Saturday and we know how difficult that is going to be. Like Northampton and Burton they are big promotion challengers and I respect there manager who I think does a great job.
''I said after Saturday that we had a very tough first 10 matches of the season and in that period we will learn so much. What I do know is that if we come through that run of fixtures and be challenging towards the top we will be challenging at the end of the season.
''We did not deserve what happened last night but let us turn the pain we feel this morning into a positive energy on Saturday."