Miscalculation

Hello folks, its only been a few years since my last foray into chess journalism, so its the perfect time to dust off the keyboard and delight my thousands of fans with a new and gleamy clean column for Chess Patzer Magazine!
When I say journalism, I mean some badly phrased sentences, and very questionable grammar all cobbled together to form a barely readable bunch of words (and that like.)
I've always said that any piece of literature should be a reflection of the author, so here it is, its not pretty, short, poor and fairly incoherent, enjoy.

As a decent standard club player around 160 to 170 ECF I've always had reasonably good ability to calculate,  (relatively simple lines anyway!) however In the very recent County Durham Congress, it became very clear to me, that what little power of calculation I had previously possessed had deserted me.
I played 4 games. A win, a loss and 2 draws, (yes I won nothing) The draws and the win I should have lost, and the game I lost I should have won!
So, my calculation has deserted me, but apparently my luck is in, if you call scoring 50% lucky.
I've gone from a number crunching Commodore 64 to a Babbage Difference Engine, difference being bloody massive!
I can't work out the reason for this, I'm playing a lot online lately, blitz mainly, which requires a rapid assessment of any given position and is played on instinct, it doesn't require long calculation of variations, generally just some short term tactical gains.
Perhaps my calculation engine has seized up through lack of use?
Maybe blitz has made me too impatient, or too lazy to properly work out any variations?
Is my increasing age or waistline contributing to a loss of brain function and fatigue?
I offer up the 4 critical positions from the games I played for your perusal.
Firstly, the game played in round 1 on Friday evening, my only win of the weekend, though as we'll see fortune was on my side CS v I.Chester
Second game, a missed win in deep time trouble D.Teague v CS
Third game, another lucky draw CS v G.Ellames
Fourth and final instalment, another half gained M.Seeber v CS
Clearly, all four games have been poorly calculated, I'm afraid its back to the drawing board for me. 
Any feedback would be most welcome, good or bad.