Dallas Mavericks play-by-play announcer Chuck Cooperstein joined JaM Session on ESPN Dallas 103.3 [KESN-FM] recently to discuss all things Mavericks basketball. Here are some of the highlights:On Luka Doncic's free throw shooting"He's got to work on his motion, he really does. It's not just simply shooting free throws, he's got to change how he's shooting free throws.