TMZSports.com
Haters can save their breath when it comes to JJ Redick ... 'cause his former teammate, Matt Barnes, tells TMZ Sports the Lakers coach simply "doesn't give a s***" about any outside noise.
Barnes played with Redick on the L.A. Clippers from 2013 to 2015 ... and if there's one takeaway he got from their time together, it's that the dude stays focused on what matters -- and definitely knows his stuff.
Now that Redick has landed his first head coaching gig (with the Purple and Gold, no less), all eyes are on him .