The Irishman says Trossard has brought something new to the Seagulls since joining in the summer after an outstanding season for Genk.
He told The Argus: “He (Trossard) is his own player, he is quite unique and someone we don't have.
“He has been brilliant, a breath of fresh air since he has come in.
“He was in good form before he got injured, which was disappointing.
“But you have got to build him up slowly and he is still adapting to a new country, a new league.
“You can see glimpses of him when he comes on and he changed the game for us."