Let's talk about the Twitter comparison. Google+ engagement looks at one minor number: public posts. Private posts (the default mode) are NOT counted. Comments, which are replies, are NOT counted. Twitter engagement numbers count public posts, too (unlike on G+, the vast majority of Twitter posts are public). And replies to tweets -- the equivalent of a comment on Google+ -- are counted, too. A post with 20 replies on Google+ is counted as one post. A post with 20 replies on Twitter is counted as 21 posts. Twitter gets more than 20 times more "credit" in this example for engagement than Google+ does for the EXACT same conversation. That's why Twitter numbers are similar to Google+ numbers when in Face Google+ engagement is probably many times higher than Twitter.