Charles Oakley says Carmelo Anthony's gotta be bummed to see Dwight Howard join his best friend LeBron James on the Lakers ... telling TMZ Sports "it's embarrassing for Carmelo" to remain unsigned.

Melo's status in the league has been one of the biggest topics this off-season ... and the superstar has been very public about wanting to play.

Even ex-NBAer Royce White called out LeBron for not helping out his guy ... especially after the Lakers brought Howard back after a less than stellar first stint a few years back.