Dzeko came off the bench to fire home an 88th minute winner against Tottenham yesterday.
"We can only pick 11 players," said Platt.
"We have a lot of players who would play in almost any other Premier League team. Edin is one of those players.
"We felt we needed an injection. We needed a little bit more height to get a platform to hold the ball up.
"We also know he is a goal threat and he is fresh.
"He has scored lots of goals this season and since he has been here he has scored some heavy goals."