Mel Kiper's Big Board: Ranking top 2018 prospects

Barkley moves up to No. 2 on Kiper's Big Board (0:50)

Penn State star RB Saquon Barkley moves up to the second overall player on Mel Kiper Jr.'s NFL draft Big Board. (0:50)

In this edition of my Big Board: Three new entrants from my last update -- which means three have dropped off -- plus some movement in the top five. There's also a new No. 1 defensive lineman.

A reminder:

  • The write-ups here won't change much week to week.

  • Keep in mind that several prospects listed here have started only one season, so my projections are based on size, athletic ability, statistics and what I hear from people around the league.

  • Speaking of size, what's listed here is provided by the schools. These numbers could vary greatly when players show up at the NFL combine. True height and weight really matter for almost every position.

Note: One asterisk denotes player is a junior, and two asterisks denote player is a redshirt sophomore for the 2017 season.

1. **Sam Darnold, QB, Southern California

Darnold has everything NFL teams want in a starter. He has a big frame (6-foot-4, 225 pounds), makes quick decisions and is an accurate, natural passer. He completed 67.2 percent of his passes last season and ranked second in the nation in Total QBR (86.8). Darnold has thrown too many interceptions to start the 2017 season -- seven in four games -- and he has an unorthodox, long delivery that will have to be tweaked. His Total QBR has dropped because of the turnovers (74.0), but he's again completing passes at the same rate -- 67.1 percent. The third-year sophomore is an exciting prospect who could go No. 1 overall in April's draft.