Stop us if this sounds familiar. A once-elite college prospect and top-three NBA draft pick gets off to a strong start, falls out of favor in his own organization, and winds up with the Nets in a low-risk, high-reward trade because of how far his stock has fallen. The player talks about how motivated his fall has made him, how eager he is to take advantage of the opportunity in front of him, to establish himself all over again. We’re taking abut the plight of Jahlil Okafor, but just as easily could be discussing D’Angelo Russell. The similarities for the new Nets teammates, who went Nos. 2 and 3 in the 2015 draft, are striking. “I feel like we’re similar in that we have a lot to prove,” the 6-foot-11 Okafor, a Chicago native, said Monday as he met reporters for the first time since the deal Thursday that sent him from the 76ers to the Nets along with Nik Stauskas and a 2019 second-round pick in exchange for forward Trevor Booker. “I think we both have a chip on our shoulder and we have a lot to prove.We’re definitely similar in that regard.”