Platt said: "I think after the West Brom game when he came on and scored two goals and we won the game, I said then we can only pick 11 players and we put people on the substitutes' bench to come on.
"That's the way that it's been at this football club, since I have been here anyway. It's the way that it is at everybody's football club.
"We've got a lot of players that would play in almost any Premier League team and we can only pick 11 of them. Edin's one of those players that can either start a game or be a substitute. He can either come off the bench or not come off the bench.
"We felt that we needed an injection, just a bit more height to maybe get a platform and hold the ball up, but we also know that he's a goal threat and he's fresh and he's scored lots of goals this season and since he's been here as well for the last 18 months when he came here in January.
"He's got some heavy goals is what I said after West Brom and I will continue to say it. He's a valued member of our squad of which we rotate but, as I say, we can only put 11 on the pitch."