Kenny Jackett admitted that his side were lacking attacking flair against Shrewsbury.
Pompey improved after a disappointing first half at Fratton, but fell behind when Greg Docherty fired home.
Brett Pitman rescued a point from the penalty spot, however, after Nathan Thompson had been brought down by Alex Gilliead.
Jackett conceded that Pompey well below par, although felt that was partly down to how their opponents fared.
The Blues boss said: “With the initiative and emphasis on us to create as the home side, we couldn’t find the right combinations.
“Shrewsbury have a big, strong back four and it was hard for us to get in the 1v1 situations that we’ve been very good at.
"With the initiative and emphasis on us to create as the home side, we couldn’t find the right combinations."
“We finally got going in the second period, when we were on top and attacking towards the home end.
“Gareth Evans forced their keeper to make a save with a good header in what was probably the best chance of the game.
“But clear-cut opportunities were few and far between for us during what was a dominant second half performance and that’s credit to Shrewsbury.
“Our opponents were hard to break down and really slowed the game, while a mistake from us got them one goal up.
“We showed some character after that and maybe the shackles came off a bit, with the crowd getting right behind us.
“I thought it was penalty on Thompson and Brett did well to put it away, but we maybe needed a bit more.
“We’re pleased to get the point overall because it looked like it was going to be one of those frustrating days.”
Jackett made a double substitution at the break, with Ben Thompson and Andre Green replaced by Ben Close and David Wheeler.
The manager said: “We needed a bit more football through the middle and felt that Close could bring that, complementing the other lads.
“I also thought that Dave’s explosiveness could help us in the wide areas because we hadn’t got into the game enough.”