"Everybody else is doing it" might be a fine excuse for a 12 year old, but not a grown man.
We should single out Slattery because he's our player and needs to be told to cut it out.
Telling other team's players to cut it out isn't as effective.
I wouldn't make a big deal of it, but I would be telling him it's unacceptable, and to get focus back on his assists and his shooting, where he is most effective.