Fred Wilson venture capitalist and Co-Founder Union Square Ventures
“ Chemistry among the Board members  is critical to a well-functioning Board  [just as it is among team members.]  Chemistry  must be strong  [with mutual respect and reliance] on each other's strengths to [make] right decisions.” Investing in chemistry should be for the long term including participating in activities outside the Board room.
“Unless [a] Director has a contractual [Board seat or a unique skill], [Wilson recommends removing that director who doesn't fit in and] replace[d]  with someone with similar skills who will in fit better.
[A] company needs a strong Board and [the CEO] must do everything [to ensure getting one including getting input from other entrepreneurs and CEOs to improve the Board].  [If certain directors can’t be replaced, Wilson advises adding independent directors] to balance them out  [to] build chemistry between the independents and the investors.” Changing 1 or 2 directors can change chemistry.
“ [A well-constructed, well-managed Board with strong chemistry functioning effectively]  is a tremendous asset to a company.” Fred Wilson, The Board Of Directors: Board Chemistry, Mar. 26, 2012; http://www.avc.com/a_vc/2012/03/the-board-of-directors-board-chemistry.html