There is quite a lot of randomness involved in the hiring process of these big corporations. The bar is high, but it's not extremely high. At the end of the day, the big corporation will have to pick one person from a pool of hundreds of qualified candidates... I doubt that they can differentiate between any of those. Instead, they probably resort to characteristics such as personality, attitude or other human biases to make the final decision. Talent only gets you into the final selection pool of 100 or so people; after that, it's basically a random draw. If the company has a really good hiring process, you might be able to use your talent to get you into a final pool with 10 other people; but then your chance of being hired is still only 10%...

It doesn't matter if you're a run-of-the-mill professor of computer science at MIT or if you're young Alan Turing; your odds of being hired are probably about the same. Sure, the bar is high but it's still weird to think that someone like Alan Turing could be rejected in favor of Prof. Joe Blow yet it happens all the time.