The Oakland (Las Vegas?) Raiders quarterback posted video of him taking his toddler son DEEP to left field in a friendly soft-toss game ... and the video is straight savagery!!!

Carr got in the father-son bonding time Wednesday ... and despite showing no mercy on his 3-year-old, he didn't even apologize!!!

"Sorry ... not sorry ..." the QB wrote of the epic hack.

Of course, it's all fun and games for DC ... he's known as a GREAT father to his three boys -- and he's constantly posting about parenting his kids the right way.

And, hey ... sometimes kids gotta learn to lose to get better, right?!?

As for Derek and his fam's future ... they're going to be heading off to Vegas shortly -- the Raiders are set to complete their move from the Bay Area to Nevada this offseason.