1) interesting content which isn't directly relevant to your business. They write a good blog, but it's always going to be an arm's length from your real business. Either you mislead users about where the content comes from, or you're up front and people realize that he blog, while good, doesn't really reflect your business.
2) the company doesn't really have bloggers for niche enough specialties to be interesting. You end up with a broad, lookalike blog that could have been written by anybody. This stops customers from engaging with your company.
The correct answer is what New Relic does with The Daily WTF; sponsor an established or up and coming blogger. Make the relationship clear. Users will appreciate your funding interesting content, while understanding that you didn't create it. If you align the audience of the blog with your customer base, I think you could get the same effect without the middleman.
Edit: this definitely seems to fall into category two. Their example posts are overly broad and not very engaging. Lots of link-baity, list-format titles which will drive eyeballs, but ultimately have poor conversion. I'd be interested in any case studies that prove me wrong, thugh