The 35-year-old sustained a head injury in the first half at Bloomfield Road, requiring eight minutes of treatment on the pitch.
Kane Ferdinand then went on to head home the winner for Peterborough shortly before the break to leave Blackpool only four points clear of the relegation zone.
Ince said: "Losing Barry Ferguson was a big loss to us.
"I said last week he was pivotal to the way we play. We lost him when we were in the ascendancy and then it stopped the play of the game when he was down for eight or so minutes.
"So that was a big blow and then to concede the goal in the 45th minute was really disappointing. We started really well; we had three or four good chances.
"We looked like the team that was going to score. The performance wasn't bad but we have got to understand that we are in a fight now.
"Teams below us are winning games and you get some weird results. As well as we did against Watford last week, we have not had a back-to-back wins since the start of the season.
"We are not scoring the first goal which is concerning, we are not taking responsibilities for scoring goals which is concerning."