This is the most crude version of data analysis, if you want to call it that. You're not even using all the data. At least you have proven that McDermott, like all NFL coaches, can be great at a moment in time and have until the end of their career to make the Super Bowl. There is value in proving what we already assume to be true, so your efforts are not for nothing.
If it happens, it probably happens with Allen. Unless he gets another star QB after Allen, but I think a coach typically only has one star QB in his career.