Yeah it's typical Na'Vi. XBOCT is a weird player, on one hand he definitely plays like a fucking retard at times and throws games for apparently no purpose other than trying to get solo kills in shitty spots. On the other hand, he's by far one of the strongest technical carry, his farming in terms of mechanical skill and map optimization is pretty insane(like check how often he's actually getting outfarmed by another carry player, shit doesn't happen often even when they're shitting their early game) and his teamfight decisions are among the best if not the best for a carry player(target choice, item choice etc). But sometimes, he goes full XBOCT and just goes feed and you don't fucking know why and what he expected to do even if it succeeded. Once in a while it works and he creates a big occasion, most of the time, just feed.
The weak link of Na'Vi isn't XBOCT imo, even though having a carry that's not consistent isn't necessarily helpful, it's Puppey. His draft is still ok even if he makes weird/ancient choices, the problem is he's just not at the pro level anymore and hasn't been for a while. He only plays a handful of heroes well enough which means his draft often rotates around these heroes or he gives himself some shit he sucks at and relies entirely on Kuroky to do the support shit, which in the recent years has been as important as carries and mids. He's still strategically a great player but skill-wise, he's dragging down the team a lot. He also randomly drafts shit his team isn't good at playing.
But anyway it's Na'Vi, they'll do their Na'Vi shit and probably do fine and get top4. At the same time this tournament has the whole 6lowest elminated right away thing and Na'Vi tends to be awful at the start of a competition, so there's also some decent odds they'll just tank right away and not even make it past the prelims.
I like that no team is dominating like crazy though. DK looked like they'd win TI4 easy a few months ago, but since then they've been losing to a lot of the other high tier teams and if you look at what's going on in china lately, they've been playing Newbee A LOT and they're about on par with them so they're not even the strongest chinese team to begin with. Younger talented teams like EG are popping up too and while not in top form you can never count teams like Alliance out, the rat is strong, so TI should be pretty amazing. Oh and the hero balance is at a great point at the moment.