I believe anyone who's played football knows an underinflated ball won't fly as far or as true as a properly-inflated one, especially when it's kicked. And receivers have all kindsa techniques, methods, & equipment to help them hold onto a pass.
I believe that if a close investigation had been made of every pro football dynasty team, there'da been some questionable, rule-bending practices uncovered. With the amounta $$ involved, teams are gonna be looking for every and any little advantage they can get away with.
As for baseball, how often do we see a MLB pitcher going to his mouth with his pitching hand between pitches, or when receiving a new ball, and the umps saying nothing?
As a former amateur pitcher, I almost-always went to a rosin bag or pine tar cloth to help me grip the ball better. That's a lot different from deliberately smearing a substance onto a ball so it drops sharply about a yard from the hitter.