He said all the right things, but you knew he would. Say this for Fernando Mendoza: He’s as mature off the football field as he appeared on it during a Heisman Trophy-winning season at Indiana. And get this: He still views himself as an underdog, as the guy who was the 288th recruit in Florida coming out of high school. And that might be the best thing about this entire No. 1 selection business. Well, you knew it was coming. After months of talk that the Las Vegas Raiders would make Mendoza the first overall draft pick, the team followed through in selecting the quarterback on Thursday night. Now, the real work begins. And there is a lot of it. Established veteran “That underdog mentality is always still there, but it’s about having unwavering optimism, and the message that my mom gave me that helped unlock the exponential growth is — ‘Don’t put a ceiling over your head,’” Mendoza said. “Although they ranked me 288th, I didn’t see myself as that, because I didn’t see myself as a ranking. I just saw me as me.…