NBA's Jeff Adrien -- I'm No Valet Thief ... Let Me Explain

File Under: I'M NO DAMN CAR THIEF ... 'cause NBA player Jeff Adrien says he's not the car stealing MORON cops made him out to be ... telling TMZ Sports his arrest was nothing more than a mix-up.

We broke the story ... Jeff was arrested for grand theft auto in L.A. this week -- after allegedly stealing a sick Mercedes from valet and taking the whip on a 6-hour joyride.

Now, Jeff is finally breaking his silence -- telling TMZ Sports he has a LEGIT EXPLANATION for the whole thing ... it was a case of mistaken Mercedes identity.

"I came out of the Hollywood hotel in a rush. My friend gave me his ticket and said use his car ... so when then valet pulled up in the ride I hopped in and left."

Adrien says he had never seen the car beforehand -- so he didn't know if the car belonged to his friend or someone else ... he just assumed he was in the right car.

"I don't like to point fingers but this is Beverly Hills, there are a ton of Mercedes rolling around."

Adrien says the fact he brought the car back to the hotel proves there was NEVER an intent to steal the car ... it was just an innocent mix-up.

In fact, Adrien and his lawyer both tell TMZ Sports the charges against him have been dropped -- though we have not been able to independently confirm that yet.