tl;dr: How to deal with programmers who are highly recommended, but cannot handle paper test programming question

I interviewed a candidate for a programming position. He is a recent graduate from a college in computer science degree.

He has an excellent recommendation from his supervisor while he was interning for a programming job, and he had a string of programming side projects under his belt during his university time. Not very difficult kind of projects, but definitely self-contained and usable websites/mobile apps. Based on the resume he looks like a stellar fit.

The only problem is that when I gave him a paper test-- basically he has to use pen and paper to answer some programming questions, he struggled and couldn't get a single one correct. My questions all are very basic programming questions-- somewhere along the level of fizzbuzz, matching an element in the array-- the kind of questions that can be easily answered by those who take one semester of entry level programming course.

And I already mentioned that I don't care at all about the syntax/language. Pseudo code is good enough for me

He requested to take the questions back for answers, which I agreed. The next day he sent me the fully corrected solutions. He did the assignments on an IDE and managed to get all of the answers correct.

This puzzles me-- if he is as good as his referral recommendation implies, why he can't handle the paper test? Is it possible that there are some people who can code well in front of a computer screen, but when comes to actually writing programming solutions down on a paper, they struggle?

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