There are more people online all the time. There are always going to be more people wrestling that stuff.
More people read about sabermetrics now than in 1999 or 1989. Hell, more read online now then read Moneyball. It doesn't mean that the revolution started today, or with Moneyball, or with Rob Neyer getting hired by ESPN (which some people point to).
That's the general point.
But it's not an "internet explosion" thing. It's something that's developed in last 3-5 years. Mainstream sports and pop culture sites (BR, SBN, Uproxx, Grantland, etc) doing wrestling coverage is probably part of it, but I'm not sure that explains all of it.