Driving first time visitors doesn't mean anything for a social network unless they have retention. Show me that Google+ visitors return to the site regularly an

Driving first time visitors doesn't mean anything for a social network unless they have retention. Show me that Google+ visitors return to the site regularly and I'll start to think this is more than just measuring the size of your car's engine to determine its top speed. Anecdotal evidence tells me otherwise -- there are tons of people on G+, but nobody uses it.