I believe there is a similarity between Einstein's Theory of Relativity and the Elements of Chess.  In Einstein's theories, he had a General Theory of Relativity and a Specific Theory of Relativity.  In chess, Force (the chess pieces), Space (the board and it's squares), and Time (the move) make up the elements of chess just like Matter/Energy, Space, and Time make up the element's of Einstein's Universe.  The specifics of chess are dynamism or active piece play representing Force, pawn structure and control of central squaresrepresenting Space, and the initiative representing Time.

The key to using this knowledge in chess is to understand the rules and then utilise the exception to the rule.  One must understand fully the 3 elements in chess and how if there is an uncompensated imbalance to be able to solve for the win.  Mastery in chess occurs when one trades imbalances to create a struggle. 

I have a problem with defense against knights ---any comments will be appreciated.

Good post, tactician. Any more responses to hptchess on how to evaluate a game, especially in the middle game?

The way I evaluate a position is something like this: Is the material the same? If not then do I (or does he) have any compensation for it? Is that compensation substantial? Are his pieces developed? Are mine? Can he create good outposts, files, diagnals which would improve his piece/s. Can I? Can he create a passed pawn? Can I? Can he exchange a piece to improve his position? Can I? Can he gain space? Can I? And so on. Based on all that and a lot more you can usually see who is better unless it's some grandmaster position in which the position will usually be good for both sides. Then when making a move I ask myself what my opponent's plan is? I look at what it is and then I look for a way to stop it while trying to continue with my own.

Is there an objective way to evaluate a game?  I suspect that many people evaluate their own... and based on a chance comment or game decide.  Not likely very accurate, but with lasting effect on the person's idea of their level of play.