"There's no one at Microsoft who was just kind of mediocre for a couple of years, and then just out of the blue started optimizing everything in sight." That's

"There's no one at Microsoft who was just kind of mediocre for a couple of years, and then just out of the blue started optimizing everything in sight." That's a fixed mindset if there ever was one. He's saying its extremely improbable for someone to go from mediocre to super skilled.