Keeping cards close to the heart and only reveal at the last moment. Drum roll, tell whole world gives what advantage? Only advantage to the opponent to react and change their strategies.
We know almost for certain which GRC will have which minister anchoring the ward. The other MPs will likely be standing in their own ward from the last election and then there are the noobs. The noobs isn't going to swing much votes over to the PAP side so the opposition. In that case, is there a need for the opposition to be so hush hush about all this. Wouldn't it be more useful for the opposition to tell the ward where they are contesting that they will be there and make their presences felt?