I think you might be right.
Mahrez and Sanchez can get into double figures easily and Giroud can get twenty or more, that's more than forty goals just from those three players.
It also means other players will get chances as well simply because our attacking players will be so hard to defend against.
If we get Mahrez, and not someone like Lacazette or Draxler, we would have more of a chance of scoring more goals.
Although both would be preferable.