Rihanna Helped Chris Rock Date Younger & Feel Better, Says Brother Jordan

Chris Rock is a changed man for the better, now that he's dating younger women -- and it all might be thanks to him getting shot down by Rihanna first ... so says his brother.

We got Jordan Rock -- the youngest of 7 Rock siblings -- and asked if Chris was aiming too high by trying to get at RiRi post-divorce, like he explained in his new Netflix special, "Tamborine."

Jordan says the Rocks know no limits when shooting their shot -- even though it didn't really work out for Chris and Rihanna. The upside ... Chris's new GF is, in fact, younger than him, and he seems to be in a better mood because of it ... according to Jordan, anyway.

Sounds like a proper thank you is in order for Ms. Fenty for helping Chris turn a new leaf. Or maybe a "Happy 30th Birthday" will do.