I think he's referring to the Democrats losing in 2000 despite having a good economy to start with. It's an argument that does have merit. Afterall, the unemployment rate was around 4% at this time and GDP growth was around 5.5%, both of which will be better than what we'll see in 2016.
However, one has to keep in mind that Bush just barely beat Gore. In fact, he lost the popular vote to Gore. So the election was as tight as it could get. And Bush had a much more favorable landscape to work with. The electoral college was much more in favor of the Republicans in 2000, as well as the demographics with an emphasis on Hispanics.
If you take away the economic narrative, how does the GOP get there? They aren't running super strong candidates. They haven't offered much in the way of ideas. They've done next to nothing to court the Hispanic voters. And elections are rarely centered around foreign policy. All they would be left with are attacks on Hillary. I don't know. Maybe all these attacks will work. But that's a big If.