I don't think you can call NAVI chokers when they only have 5 match points, otherwise they closed out their maps. I think they probably just faced two good teams in DRX and LOUD that had better ideas to counter NAVI's play style (triple controller lol). You look at other teams and see how many leads they just blow (like EDG, who have a hard time closing games on match point) and NAVI doesn't look too bad.
TLDR: Navi a bit unlucky, other teams choke more