THE RANKINGS SO FAR - No. 15 - The class of 2011 | No. 14 - The class of 2012 | No. 13 - The class of 2015 | No. 12 - The class of 2005 | No. 11 - The class of 2004 | No. 10 - The class of 2014 | No. 9 - The class of 2003 | No. 8 - The class of 2010 | No. 7 - The class of 2009 | No. 6 - The class of 2008 | No. 5 - The class of 2016 | No. 4 - The class of 2017

There are a few categories of recruiting classes that have popped up in this countdown. Chief among them - and accounting for seven of the 15 classes - are transition classes and first full classes.

The transition classes are classes that a new coach inherits and has to finish between the time of his hiring and Signing Day. Those classes don't tend to have great success rates, for a variety of reasons.

First full classes are the next classes, the ones that new coaches spend a whole year building. Those classes have turned out to be some of the best Pitt has signed since 2003.

The class of 2016 was Pat Narduzzi's first full class, and it ranked No. 5 on this countdown. At No. 3, we have another first full class, and this time it's Paul Chryst's class of 2013.

Chryst had been hired in December 2011 and spent the next two months rebuilding a mess of a class that he inherited from Todd Graham. Once he had that project complete, he moved on to his first full recruiting class and it turned out to be the best class he recruited at Pitt.

Here's what the class of 2013 looked like on Signing Day.

In terms of players who became contributors or better, the class of 2013 has more than any class since 2003, as more than a dozen players from the class worked their way into the starting lineup over the course of their careers. There are caveats to that, of course, like the fact that 27 recruits signed with Pitt in the class or the fact that the 2013 class came on the heels of two classes in 2011 and 2012 that had high washout rates.

But it's still hard to deny the success of the 2013 class. It produced two of the biggest stars to play for Pitt this decade in Tyler Boyd and James Conner, plus an NFL Draft pick on the offensive line in Dorian Johnson.

And the depth beyond the star players is pretty impressive. Scott Orndoff, Tyrique Jarrett, Shakir Soto, Alex Officer, Jaryd Jones-Smith, Ryan Winslow, Chris Blewitt, Jeremiah Taleni, Terrish Webb, Matt Galambos, Jester Weah and Jaymar Parrish were all significant contributors during their careers.

Pitt's success in 2016 can be tied directly to the 2013 class. In the win at Clemson alone, Conner had 132 yards and a rushing touchdown plus another receiving score, Orndoff caught nine passes for 128 yards and two touchdowns, Parrish had a big 44-yard reception, Galambos recorded 12 tackles, Taleni came up big on a fourth-down stop and Lewis made an interception in the end zone (the second time he did that in a big game that last season).

Beyond the 2016 season, the class also brought Boyd, who finished his career as Pitt's all-time leading receiver and became a second-round Draft pick.

The 2013 class had its share of busts, of course - the loss of Tra'Von Chapman as a four-star quarterback recruit hurt - and Robert Foster's decision to skip Pitt for Alabama is part of the story of the class, too. But overall, the 2013 class brought some big-time contributors to the Panthers and stands as one of Pitt's best this century.