Apart from his loan period Idah hadn't been an established thing at Celtic that they need a replacement for. He did not nail a starting position, he ended up becoming a spare part, unlike say Kyota or O'Riley, who were established. Celtic certainly need forward players but not a replacement for a player who failed to make his mark. Rodgers prefers the lone striker supported out wide by wingers such as Maeda on the left and whoever on the right.