I guess I would ask if you've used the word deflate in any text in the past year? You may say only in reference to this case, only joking about it. So if you were accused today of deflating balls there's likely more evidence on your phone of the term deflate than on McNally's. Yet the term only appears twice by a man who deflated things as part of his job, and a man who admits one of his responsibilities was to get the refs to deflate balls 12.5 if the ref overinflated them. Which had happened.
I've used the term repeatedly in reference to ego's, testicles, court cases, etc since it entered my vernacular months ago. So I would submit that if the word deflate is a term you've used without cheating in football it's unreasonable to say McNally couldn't use it the same way since it entered his vernacular through his job. It's just as likely for McNally to use it for other than cheating as it is for us all to use it for other than cheating or even other than football.
Now if we can establish its possible to use the term in many ways then we look at the texts to see if it was ever used for other than football deflation by McNally. The term was used twice. Once during a Packers game when McNally was not at the game. "Deflate and give somebody that jkt" was said while Jastremski held a jacket on TV.
What does that mean? I don't know except it has nothing to do with deflating footballs so we have established 1 of 2 times used it wasn't about cheating, or even about footballs. So like us, he does use the term outside of its dictionary definition.
The second time the term was used it was in the off season so again it couldn't have related to cheating in games. So I suppose it's open to interpretation, and that text essentially is the NFL's entire evidence. A text that said deflator in the off season. A word that we have proof was used by McNally for things that don't have to do with footballs.
But the NFL says that text must relate to footballs, even though the one other time he used the word it didn't. IMO Occam's razor points the term relating to something other than footballs in the second example, just as we know it had nothing to do with footballs in the first example.