Then he needs to find a way to use it. Brunson bumps into people and dislodges them. While I saw relatively little of tape on Clayton I don't remember seeing him doing it. Clayton tends to run away/fake/screen defenders to create space instead of going into their body.
Walter seems to need a lot of empty space for his shots and the NBA defenders are unlikely to give it to him as readily as in college. It is actually Collier who plays more like Brunson on offense (minus his jump shot, of course).
Brunson is also 28 and already has his "man strength." Walt is an old-man by draft standards but is still only 22. He'll naturally get stronger as he reaches peak maturity. And it's not like Brunson set the world on fire in years 1 and 2. It definitely took him time.