By Julie Kliegman How closely have we been paying attention to the underlying messages of athletes who speak out about their mental health? New Nets guard Ben Simmons spoke publicly Tuesday for the first time in months after he wastraded from the Sixers for James Harden and Paul Millsap, along with Andre Drummond, Seth Curry and two first-round picks. Simmons reported to the slumping team Monday after sitting out the start of the 2021–22 campaign, having cited mental health concerns. Not everyone took well to the positive development in Brooklyn this week. “So much for Ben Simmons mental illne…