Looking at the top 5 players on the final standings of the recently concluded FedEx Cup, it's pretty clear to see how they separate themselves from the rest.
A season is not a week
Any player can win a tournament with a hot putter. Nobody finishes a season at the top of the standings that way, because putting swings around from week to week far more than ball striking does.
The consistent thread through the top of any season long race is tee to green performance.
Approach play carries the load
Of the tee to green categories, approach play is the one with the greatest spread between the best and the rest. It is also the most repeatable.
Players who control both start line and distance with their irons generate more birdie chances every single week, regardless of course setup or conditions.
Applying it below Tour level
The same hierarchy holds for amateurs, only more severely. Approach play and avoiding disasters explain most of the gap between handicap brackets.
If your practice time is split evenly across the bag, it is almost certainly split wrong.