Ladder is infuriating!

Hi everyone. I am a Protoss player on the EU server.

I have played 4 games this evening. After losing the first 3, I rage quit out of my league (diamond). I had been in diamond league close to 3 years, and been in masters once during that time.

I am always improving, practicing each match up one at a time getting better, but it never seems to reflect in my ladder results. I am constantly faced with situations that kill me, because my opponent makes a strange play eg. A Zerg opponent with poor macro, who as a result has a large bank to make an army at a time where they normally wouldn't.

After leaving the league, I played my placement match, it was a PvT. The game was pretty standard, gateway expand vs reaper expand. Standard 10 minute push which was easily defended. The only major mistake I could spot in my play was late game probe production, for some reason I stopped on 56 which is unusual for me, if anything I usually make too many.

The end result was a victory for me, with 103 kills and 8 units lost. This was against a platinum who has been an 8 time master player.

Please feel free to watch my game and Criticize my play, would love to hear your thoughts, but in my head at lest, I was playing at a higher level than a platinum player.

Sorry for the rant but this ladder nonsense of constantly facing former masters has really got to me recently, anyone else facing the same situation?