Cheryl Morgan has written about the solution the Hugo Administrators in 1994 (including me) took when faced with a similar 5% drop — we relocated two shorter Novelettes into Short Story, "filling out" the category. We caught hell for it. David Bratman, who was the public face of Hugo Administration that year, has filled in more of the details. I apologize for the places where I got the year wrong on that story. David, Seth Goldberg, and I were Hugo Administrators in both 1993 and 1994, and when re-telling the story of the relocated works, I flopped the years.
One of the reactions to our decision in 1994 was that a huge number of people, presumably prompted by Mike Resnick's fury at the decision, poured into the WSFS Business Meeting in Winnipeg to pass a constitutional amendment that reduced the "gray zone" between categories from a flat 5000 words to 20% of the category boundary size, which probably was a good idea anyway.
One thing I remember as part of the head table staff that year was that we had a room that would ordinarily been considered too large for the Business Meeting. (This is a function of what size rooms the Winnipeg Convention Centre had; given the choice between too small and too large, I always take too large.) By sheer coincidence, we ended up with the right sized room after all. The turnout for that and one other hot-button issue of the day with a completely different constituency was, relatively speaking, vast. Considering that there were only about 3,500 bodies on site at ConAdian, I would not be surprised to find that the Business Meeting attendance measured as a percentage of attending members was larger than any time since the 1960s or even earlier. It wasn't quite as large (in percentage terms) as the Westercon 64 Business Meeting, but it was still impressive.