A Fresh install of Chromium Version 57.0.2987.98 installed from the repositories provides the behavior you desire. "right-click on a link and click "Open link in new tab" the new tab opens loading resource in background.It's available via the software center as seen below:
As you can see, I don't experience this issue with a clean install and no extensions enabled:
EDIT: If you are still experiencing this difficulty it's likely due to one of the plugins that provide this behavior that you may have forgotten that you installed. OR you are launching chromium with a flag set which you didn't mention in your question that is causing this problem for you.
Further edit: Launching with only
--auto-open-devtools-for-tabs flag set does not cause this behavior. It seems that this problem only occurs when launching with both
--auto-open-devtools-for-tabs flag and
Testing.on 64 bit Xenial 16.04 LTS (Unity) & Xubuntu 16.04 32-bit (XFCE)
How to disable chromium focus to new tab when clicking link?