FLORHAM PARK, N.J. -- New York Jets defensive tackle Sheldon Richardson was the 13th overall pick in the draft back in April. But he is playing with a chip on his shoulder.

ESPN draft expert Mel Kiper Jr. posted his NFL Rookie Rankings on Thursday, and rated Richardson the No. 1 rookie in the league. When informed of this on Friday, Richardson smirked.

"Mel Kiper had me the third [defensive] tackle getting taken off the board," Richardson said. "[He said] I wasn't a good run-stuffer."

Rookie Sheldon Richardson continued to impress with his effort against Atlanta on Monday night. AP Photo/John Bazemore

It's true -- in early April, Kiper had Richardson rated as the third-best defensive tackle in the draft, behind Sharrif Floyd of Florida and Star Lotulelei of Utah. But by the time Kiper released his final mock draft, Richardson had risen to the No. 2 defensive tackle.

In the end, Richardson was the first one taken -- one spot ahead of Lotulelei, and 10 spots ahead of Floyd. And Richardson has proven worthy of that spot, with 24 tackles and 2.5 sacks in five games.

"He's been consistently disruptive," Kiper wrote, "showing tremendous quickness and athleticism, eliminating the chance for blockers to move him and then getting to the second level."

"I don’t think about what people say good about me, I know what I do good," Richardson said. "I take it with a grain of salt. Thank you for the compliment, but I knew this was gonna happen."

Richardson's confidence is striking. The Missouri product said Friday that playing in the NFL hasn't been a big adjustment, and he expected to be making this big an impact right away.

"Most definitely did," Richardson said. "You can go back to my interviews at the combine, I said I'm trying to be the top pick in the draft. I feel like I am the top pick in the draft, and I’m trying to be that."

He's quickly become a key component of one of the best defenses in the NFL. The Jets are ranked second in the league in yards allowed per game (299.0), first in rushing yards allowed per attempt (3.0), and tied for fifth in sacks (16).

Richardson has gotten to the quarterback twice in the past three weeks, including an up-the-middle takedown of Atlanta Falcons QB Matt Ryan on Monday night.

And he loves playing for Jets coach Rex Ryan. "He's real, he's a genuine person," Richardson said. "It might be ugly to some people, but it’s real. We respect him for it."

Fellow rookie Geno Smith is getting more attention, which is natural given the position he plays, and his brilliant performance last week against the Falcons. Kiper ranked Smith fifth among all NFL rookies through Week 5.

But Richardson may be making just as big an impact on the other side of the ball.

The Jets have several young, talented players on defense. But Richardson may be the most talented of them all.