How come a player such as Lang with great chess memory is only a FM?

There is a study that shows that GM most of the time recall pattern knowledge while playing chess. So how come a player such as Lang that posses great chess memory is only a FM? 

http://www.chessvibes.com/reports/fm-marc-lang-sets-new-blindfold-simul-record-of-46-boards

Because he takes more than just memory to be a strong chess player.  There could be a thousand different reaons whe he isn't a GM

Let's make it happen!

I think its partially since he is a computer programmer. 

He isnt fully devoted to chess.

and @sisu, the games are on the article.

i dont know if you can download it as a pgn.

There are people who can memorize whole telephone books, but it doesn´t make them great conversationalists.

Maybe he needs more of a fighting spirit, will to win, and be more at one with himself? 

@ basilicone

That logic is difficult to apply here because blindfold chess is so much more related to regular chess than telephone books to conversations :P. 

I'd be willing to bet it's lack of desire. Or maybe he is one of those guys that has excellent board vision but just can't find opponent responses or he is not able to evaluate the position like a GM.

But it definitely would take a load off if you could just close your eyes and pretend to sleep while doing calculations in your head. When he makes a move just open one eye and go back to "sleeping"

That would psych your opponent out for sure!

Let's make it happen!

The comparison was based more on the huge number of memorized openings than on the blindfold bit: you use the telephone numbers to ring people up and talk to them; you use the "numbers" of a book line to sit down and start a game against an opponent. And once the numbers have served their purpose, the rest is up to you, in both cases ... geddit? ;)

Thats quite a logic leap my friend. In any case, I think that his "book mind" could only take him so far. That I will agree with.

In my opionion I was basically lacking talent, paired with a good portion (excessive amout) of laziness. When I was a kid, I really wanted to become a grandmaster one day, but I never came even close. So I finally turned to something that was more likely to pay my bills :-). Moreover, just memorizing and visualising doesn't make you a strong player, so I really like the image with the telephone book :-).