IN WHAT looms as one of the tightest NAB AFL Rising Star races in history, a recent quiet run could hurt Port Adelaide onballer Sam Powell-Pepper's chances.

The young gun had just six disposals and conceded five free kicks against Adelaide as the Power was thumped in the Showdown last Sunday.

Since round 16, he has averaged only 1.4 points per game in the Schick AFL Player Ratings. That's well down on his season average 9.5 points per game, having lined up in 19 games.

However, the big-bodied midfielder's excellent early form could be enough to see him take the prize.

The other two seen to be leading the race with the West Australian to be named the Rising Star are both defenders: Hawthorn's Ryan Burton and Essendon's Andrew McGrath.

Burton has averaged 9.8 points per game through 18 matches, while last year's No. 1 selection McGrath has averaged 8.3 points from 17 matches.

Crucially with that pair, the drop-off since round 16 has been very minor. Burton's rating is 0.9 points down in that time compared to his season average, while it's just 0.3 for McGrath.

Schick AFL Player Ratings: Who are your club's leaders?

Player Ratings are calculated by Champion Data and take into account an individual's performances in their last 40 matches over a rolling two-year period.

A couple of Carlton's exciting prospects have delivered. Charlie Curnow (8.9 average from 18 games) and Sam Petrevski-Seton (8.8 average from 17 games) have thrilled Blues fans, spending time up forward and in the midfield.

One person who almost certainly would have been in the running with more luck was Brisbane Lions defender Alex Witherden.

After missing most of 2016 – his draft year – with a badly broken leg and having suffered a couple of hamstring injuries, his debut with the Lions was held back as he spent the first half of the season in the NEAFL.

Since making his debut, Witherden has averaged 8.1 points per game from seven matches and will be one of the leading contenders to take the award out in 2018.