One of the points that limits Q&A sites like this one is the somewhat stricter format. Sure we have comments as well, but they are highly volatile and anyway not meant for discussion. It won't appeal to everyone the same. As a community we often tell newcomers that this is not a forum. So when comparing to Reddit I think you're comparing apples and oranges. I didn't know AllDevOpsDay until I read your question, but it also looks like quite a different format as well.
But I am with Bruce Becker on the other point. The numbers about posts and users don't say a lot on their own. The benefit to the internauts visiting is what makes a Q&A site successful. When I ask my colleagues at work if they've heard of StackOverflow and various other StackExchange sites they will all readily admit to reading and benefiting from answers (usually through web searches and several times a week). But only a very very small percentage takes the step to posting their questions. It could be that their question had been asked already and was also answered or that some information they gleaned from one of our communities gave them a nudge in the right direction, but in any case that first step seems to be a big one (although I wouldn't say it was). And then it seems to be yet another big step to start answering or voting or in other words committing to your community/communities; despite all of those gamification incentives (badges, reputation, privileges ...).
Not sure I'd buy into "social traffic" (and not just because of the misleading terminology). In terms of traffic and ads played out to visitors it may be true that this is the most attractive part. But that would be what the company behind StackExchange cares about, not so much the individual communities. In fact I think that because of how social media works, this isn't exactly the traffic that is helpful for those trying to foster the community. I would think that visitors from search engines are more important by far and that optimizing for clear titles of the questions and correct tags and terminology would be a better path.
I guess what I am trying to say is that the formats you compare differ too wildly and that certain of the naked numbers won't tell you about the utility the site provides for people who are not (yet) part of the community.
And last but not least there is that little issue that many of the topics a DevOps staffer cares about is also catered by at least four other SE communities. So you're in a competition and some of those other communities are giants. So despite the age of this site and a bunch of committed core community members it's still a David vs. Goliath situation from my point of view.
