Handful= 7 episodes? 3 discs will need replacing.
Yes, a handful is normally defined as a small quantity, more than a few but less than several, usually between 5-8, when not discussing a more specific measurement (such as a handful of peanuts).
Haven could simply be one they didn't watch, it is one of the weaker episodes of the season.
I'm not justifying that this slipped through, merely trying to point out that it's not completely unreasonable given the large amount of material they were provided with and the need to post reviews quickly for them to make money off ads. Not as many people will read a given review if another site has had one posted for a week and a majority of the audience has already gotten the information they require.