Yes I agree! You should strongly urge your client to add content to the home page of their site. As Bruce and Ray mentioned above, the home page is the FRONT DOOR of your site. This tells both your visitors and Google "What you do" and "Where you do it".

Always be sure to make a STATEMENT on your home page!

I agree with SilverDoor & donford!

Relevancy! Relevancy! Relevancy!

Don't get too caught up in your domain authority or page rank. Build naturally (for the users of your site)... and it all shall come

From a UX perspective: This allows the visitor to refer to the linked page/info but be able to continue on with the article/page from your site.

From an SEO perspective, IMO This helps your bounce rate from jumping when people engage the links you have on your site.

Check out this previous Q&A posted by our buddy Max Minzer! Hope this helps with your question!!

http://moz.com/community/q/when-is-it-good-to-use-target-_blank

I agree. You should get with your host and review your websites server stats. This will give you more detailed information about where the traffic is coming from. Hopefully not bots!!

In the event that it is, this would explain why the average visit duration has dropped so drastically.

Also keep in mind that if there is actual new traffic coming to your site (not bots), this could also be contributing to the drop in visit duration as new site visitors tend to spend less time than a returning visitor.

Hope this helps!!!