Pompey went three down at Shrewsbury before fighting back with two second-half goals to make it 3-2.
For the most part, the Blues were clearly not at their best, especially during a woeful first half.
It was unlike the Pompey which had performed so well in recent months and Whittingham feels it was down to ongoing talks over keeping the players at the club.
He said: ‘There’s a lot going on in people’s heads at the moment, a lot of talk about who is staying and who is going and everything else that has been going on.
‘I suppose that happens who you have a group of players who aren’t quite sure where their futures are.
‘You can say it is easy going out and playing 90 minutes of football but there are things to think about,
‘We scored and that gave us a bit of a boost. Then we scored another one with 10 minutes to go and you thought that was a chance.
‘But we just didn’t get that one other chance.’