Nice question. And certainly a good thing that you try to figure out 'where are things going wrong'. A sign that you are willing to grow.
I think the answer to your question is going to disappoint but it's really "yes and no". Because the bottom line is not in having a blog as much as it is of crafting your own self so other people can see it.
What Andrew has been very very good at doing (and much like other hot shots like Gary Veynerchuk, Chris Messina, Seth Godin, etc...) is to craft their public self. That helps them to surface and be seen as 'the reference in their field'. And by 'the reference', it really means 'the public visual attainable' reference. Because maybe there are people that are a lot better but you don't see them?
So, to answer your question, if you have something to say and that thing helps move the world (although it doesn't have to be game changing), then yes. You should get on doing a blog. Talk about things that define you though. Do not try to play the game of someone you're not, as it will not serve your later, quite the opposite.
To your question "how to land a director job", I think you've eluded in a large part 'what is their expectations' and 'why are you falling short'? I would recommend to do a deeper analysis in that direction rather.
Last question I would ask you is "why do you want a director-level job so much?".
Finally, Gary says (very often) that some games are just patience games. 5 years isn't all that much. Might just need a bit more time.
Hope that helps.