Diablo
The Me109, when it appeared in 1935 I believe, was the best fighter of the world. It remained such until the Spitfire came along, I believe first flight in 1938.
Even so, early Spits, up to MKIX IMO ,were just equal to their contemporary 109 variants.
Basically, the 109 was updated with better armament and more powerful engines throughout its career, while handling deteriorated as weight increased.
STtill, up to the end of the war it remained better than the P40, P38,P47,Hawker Typhoon and many other fighters of WW2.
In conclusion, I don't agree with your evaluation of the 109 being of average quality.