“In theory, theory and practice are the same. In practice, they are not.”
I believe he spoke these words in an address to NASCAR.
Your point about the difference between theory and reality is well taken. There are a number of modifying factors: mostly between an air-temperature measurement in the weather station, and the temperature of the gases inside the football. Most of these push the measurements further to the extreme.
The hot field and further heated ball on a sunny day; and a wet ball being subjected to evaporative cooling at the other.
Here is a report by a group of prominent engineers and physicists:
https://cbsboston.files.wordpress.com/2016/05/physics-professors-deflategate-filing.pdf
Nice graphs in Appendix B show how often from temperature alone footballs would be out of specs.