The Big Baller appeared on the "Doug & Wolf" show in Arizona on Tuesday morning ... and ripped Walton to shreds.

"The Lakers gave my boy that losing attitude. If you look at my boys, the one thing they do do is win … my boys don’t lose too much."

"When he got to the Lakers -- Luke Walton was the worst coach ever for Lonzo because he had a losing mentality. They’ve been losing for three years. That’s how you develop losing.”

LaVar's comments came just a day after he told ESPN if Lonzo is indeed traded -- he wants the point guard to be dealt to the Phoenix Suns ... not the New Orleans Pelicans -- as has been rumored.

Of course, Lonzo's been one of the key pieces New Orleans appears to be seeking in a trade for superstar Anthony Davis.

Clearly, LaVar's upset about all the talk ... and he issued yet another warning to Lakers brass when it comes to trading Lonzo.

"Like I told them before, if you trade my son, it’ll be the worst thing you ever did for your franchise, I guarantee it.”