I think it really depends on how you want to run it. I think one way you could do it so there are four winners is by having the positional awards be purely stats based awards. Then the player of the week award could be somebody who had a really really good day but also was key in their team winning.
Here is an example:
John Doe 29 carries 129 yards 2 TDs 3 catches 15 yards 1 TD
RB of the week
Jane Doe 31 carries 112 yards 2 TDs (Game winning TD in 4th quarter) 1 catch 7 yards
Player of the week
Here is an example:
John Doe 29 carries 129 yards 2 TDs 3 catches 15 yards 1 TD
RB of the week
Jane Doe 31 carries 112 yards 2 TDs (Game winning TD in 4th quarter) 1 catch 7 yards
Player of the week