Depending on the battlefield circumstances, you may be right.
When I was a tanker in the army we abstractly described a tank as a triangle with each point representing in turn, firepower, protection and mobility. The area or "sum" of the triangle was its effectiveness.
On top of that you would apply battlefield tactics to make up for any shortcomings or to improve your strong points.
So yes, its alot about tank technology, but battlefield tactics can help overcome or improve the odds.
Consider the invasion of France in 1940 where the German tanks were inferior to those of the enemy but still won the day due to tactics(and some strategy heh).
Also consider "Die Maus" with heavy armor and armament but almost no mobility which meant it was probably about as useful as a pillbox...