Grandin, who returned to the Seasiders' first team last month following a spell out of favour with former boss Ian Holloway, was substituted after half an hour of last weekend's 2-2 draw with Watford.
Blackpool were 2-0 down at the time and replacement Tiago Gomes started against Blues alongside Isiah Osbourne, with Ludo Sylvestre dropped to the bench alongside Angel Martinez.
"It was just tactical, having the right balance on the bench more than anything," said Appleton of the decision.
"I think with having Angel Martinez there and Ludo Sylvestre I just didn't see the point of having an extra midfield player in there.
"We had the balance with the defenders in terms of two full-back and two strikers on the bench as well so it was just getting a balance right on the bench."