If you like the Cavs or LeBron, I would steer clear of Pro Basketball Talk. The guy who wrote the article is a dedicated LeBron hater and is not a good analyst. He's more of a regurgitator of information rather than someone who can produce independent basketball insight.
The Cavs are the favorites in Vegas to win the title. I would not favor them over the continuously underrated Spurs, but I would favor them over any other team. Including the Bulls. If both teams are healthy, the Bulls aren't going to beat the Cavs. At least not with the rosters each team has presently.
The way to know that this writer dislikes the Cavs is to read his first paragraph, which is a shot at Gilbert and the team. The author comes from a Lakers blog background and for whatever reason just has never given LeBron a fair shake that I can tell.
As far as what the piece says about Irving's defense, the author got into a Twitter fight the other night with another basketball author over Damian Lillard being cut from Team USA and Irving remaining with the team. One of the first things that the author of this piece did was discuss Irving's defense as compared with Lillard's. After he was presented with statistics that seemed to go against his argument, he then chose another line of argumentation.
This "solid Irving defense," then, seems like the author's way of continuing that argument via his piece. I'm not saying Kyrie can't play good defense, but it's not something we've seen a lot of in the past.