Joe Root is no fool, he has been thinking about this for quite some time. His failure to convert is not a new thing and the odd thing for Joe is that when he does get a hundred, he invariably goes on to get a big hundred, if not a double hundred.
So it has become a mental issue. Part of me still admires the consistency of the bloke. You look at his stats in the last year and they are phenomenal, he scored half-centuries in 16 of his last 18 Tests - that in itself is something to admire.