It is fairly well known that Eric Clapton used a piece of of wood to block his trem system. However, when I tried researching the why I only found what seemed to be a bunch of unsubstantiated claims (not all of them were unsubstantiated) on what it did or improved, that is, no one really offered a solid piece of evidence back their claim up. Generally these claims were, a) it improved the tuning stability and b) it changed (often positively) the tone. Accordingly, how does this piece wood improve or hamper the tuning stability? Furthermore, what changes does it make to the tone of the guitar if any? Is there other things this wood block changes?
Essentially, I am looking for answers that can give clear explanation of the pro and cons of this wood block and a explanation of the hows and whys it positively or negatively effects the guitar's tuning, tone and so forth. Physics/engineering concepts encouraged, but not required.