I clearly answered the set question by saying Lara was better.
No, genius is clearly identified when it is seen. It's that quality that lets a person do what seems beyond the ability of other people. Pele, Maradona, Ali - you know it when you see it.
Lara has it, Gavaskar - brilliant though he was - did not.
As far as subject of the thread is concerned, the answer is pretty straightforward as you have given in your above post.
But beyond a point, classifying someone as a genius or not, does become vague and subjective.
For example - would Sachin (not Gavaskar) rank as a genius in the same category as Lara?
Here, in my opinion, it becomes subjective.
To me Sachin was every bit as much a genius as Lara was.
While Lara's genius is pretty much in-your-face, Sachin's genius is more subtle.
Sachin's unique ability to time the ball while playing it extremely close to his body is sheer genius to me. This enabled him to score runs by just playing classical cricketing shots often against good/great deliveries without taking risks. To me, that in itself is a genius.
To me, genius needn't always mean - to be unconventional, unorthodox and overtly flamboyant.
Another aspect of a genius (to me) is, they make extremely difficult things look ridiculously simple. So much so that you might completely miss it when you see them perform. Only when you attempt to duplicate what they have done (or see others trying to duplicate them), you realize - "Whoa... hold on a second here..."