The centers drafted after Wennberg in the first round:
Curtis Lazar - split time between the Sabres and Rochester this year, best season was 20 points
Frederik Gauthier - 12 points in 61 games for the Leafs this year, best season was 14 points
Michael McCarron - 2 career goals in 69 NHL games, spent the last two seasons in the AHL
Marko Dano - hey, we know that guy, 0 points in 3 games for the Jackets this year, 0 points in 8 games for Colorado last year
Jason Dickinson - 21 points in 65 games for the Stars this year, 2 assists and -6 in 15 playoff games in the playoffs
2nd round centers in 2013 have a combined 68 points in the NHL led by Jacob De La Rose
Mattias Janmark-Nylen is the only third round center who has done anything, 21 points for the Stars this year, 5 assists in 14 games in the playoffs. Carter Varhaeghe did finally break through to the NHL this year to play 52 games for the Lightning.
Andrew Copp (best season - 28 points) and Tyler Motte (hey, we know that guy) were 4th rounders.
Alan Quine has had the best career of centers drafted in the last 3 rounds in 2013. He split time between the Flames and AHL this year and has 28 career points.
Note: I went by positions and stats listed here.
2013 NHL Entry Draft Picks at hockeydb.com I did look up playoff stats for the 2 Stars and Varhaeghe just to see if they were busting out in the playoffs.
What is really interesting is that none of the centers picked after Dano would be playing ahead of Riley Nash.