There is already a code of conduct that covers the flag/anthem ceremony before games.
Even if they didn’t properly salute out of ignorance (which isn’t the case, they know what they’re doing), it would still be shameful that grown men never learned how to properly salute and show allegiance to the flag of our country. Kindergarteners know how to do this.
But then, the overpaid thugs were deliberately disrespecting the flag of the nation which gave them the opportunity to become rich just for being able to run fast and throw a ball. And they think that gives them a grievance?!