Bestman, that's a normal effect in all areas. Progress is very rarely linear. I am (amongst other things) a guitar teacher and I often get students who have 'hit the wall'. I then tell them what they've done wrong and show them how to correct it. Initially this will generally cause a drop in performance (e.g. while you get accustomed to a new technique) but once it has 'clicked' the student will improve past their previous level. then of course you will normally hit a new wall (at a higher level than previously), and the process starts over again.
I presume the same happens in chess progression. for example, you may learn about a positional theme. The first times you employ the theme in an actual game situation you are likely to mess up a lot, thus experiencing a drop in performance. However once you become comfortable with this new theme you will be able to take your game to a level you weren't previously.
Of course these are very simplified examples. there are lots of factors influencing progress, but generally it's down to hard work. Unless you are Magnus Carlsen talent plays a very little role (which is actually quite nice for us 'untalented' people - there's hope yet
).
