Kenny Jackett believes that Pompey were naïve in their defeat to Northampton.
Chris Long’s strike and a Matt Clarke own-goal had given the hosts a comfortable interval lead on a rain-soaked evening at Sixfields Stadium.
But Matty Kennedy reduced the deficit and there were plenty of other chances to raise hopes of a comeback among the travelling supporters.
Long added a third for the Cobblers against the run of play, though, and Jackett was unhappy with the way it was gifted to him.
The Blues boss said: “We certainly could have won that game and there certainly wasn’t a lack of application on our part.
“But there was a touch of naivety about us at times and we need to be more streetwise. We have to learn.
"There’s a naivety to us, but on the plus side there’s also plenty of enthusiasm."
“The third goal summed us up. Kennedy runs off to get a drink, it was a poor strike from the keeper, the balls in our area and all of a sudden we’re 3-1 down.
“That was a period when we were working hard to get back into the match and you can’t let sides have that numerical advantage, even for a few seconds. It’s unprofessional.
“We had another player running off to get treatment for a bloody nose. If the referee sends you off then that’s fine or you go down – you don’t run off the pitch.
“So there’s a naivety to us, but on the plus side there’s also plenty of enthusiasm, a good attitude and no lack of ability.
“We created a lot of chances and for us to turn into a consistent winning unit we have to be right up there.
“It’s a work in progress, but you don’t come up against bad sides in this division and Northampton were good at what they did.”
Kennedy’s goal was his first in a Pompey shirt and Jackett was pleased with the on-loan winger’s overall display.
He said: “Fair play to Matty because generally he played very well, but we need to show more experience in certain areas.
“He’s a good player and deliverer of the ball. He has a lot of confidence and I’m pleased with what he’s brought to our side.”