Focus with a set aperture

Image 1 Front focus, By focusing on the glass at the front of the photograph the eye is lead into the photograph, it also shows the small detail around the base of the glass where there is some crackle glass effect to the front of the glass. I prefer this photograph as I like the way the eye is drawn into the photograph. it leaves you wondering what else the photograph has to offer.
Image 2 Middle Focus The centre glass is in focus again showing the curve of the glass however the base is not quite as sharp as image one I think this is because more of the main body of the glass is in focus which could have been my fault I may have moved the camera very slightly.
Image3 Rear focus. Once again the curve of the glass and the stem are in focus but I don't really like this photograph very much as the eye is drawn straight to the rear of the photograph and you get the feeling that either the photographer was trying to take the eye straight out of the picture without you really having a chance to look at it as a whole.

What have I learnt about focal points: I think that there is an obvious focal point in most situations however I also think that at times you can bend the rules slightly and move the focus point off centre.