You're telling me the sky is blue?
Of course they don't. The top players get custom-made stuff, entirely built to the exact specs they want, and endorsements are only there for the sake of $$$$$$$$$$$$$ merits to the brand that pays them for advertising. A paint-job left, right and center, and tons of folks apparently believe they'll be the next Fed, Nad, or Djoko, as soon as they spend their bucks to get the next
'very special' racket.
Haha. It's like getting a Fender Strat and then think you'll sound like Jimi Hendrix. It's called 'advertising', mate.