I think this is the issue:
Years ago, many were not involved in politics, so they relied on the VAAD to meet the candidates and issue an endorsement. Today, many people are politically savvy, and they already have opinions about who to vote for. There still is a huge benefit to vote as a block, but people won't just swallow that without a good justification. The problem is that many of the reasons the VAAD would want to give are not things you can write publicly. So they just started losing their credibility.
I think they need to be much more upfront with their reasons, even if it means saying things that they would rather not say publicly. Without giving explicit reasons, they will continue to lose their influence more and more each year.