A pardon is not used when you think the crime occurred but the punishment is too harsh. That's a commutation (which the president also has the power to do). It can replace the punishment with a lighter one or none at all.

A pardon is used when you want to erase the criminal record on top of that.

Then commute his sentence to time served. Don't pardon him, which says he wasn't guilty to begin with.

A full pardon means the individual gets their legal record cleared (as if the crime never happened).