I go to plenty of board meetings. There are board members who do not contribute their opinions. I always want to know why someone comes to a meeting and does not have anything to say. Is it possible that they always agree with the majority?
My concern is that these people do not agree, but do not feel comfortable enough to say so at a meeting. The board chair should be keeping track of those members who do not contribute their opinion and meet with each member individually to find out why they are silent. A board member should not be playing the part of a statue at a meeting. A board member is at the meeting to contribute their opinion.