You've heard of the rookie wall. It's the mental or physical wall that a rookie seems to run into later in the season. Not only is the NFL a more physical game than college, it's a longer season. Most college teams play 13 games while the NFL regular season is 16 games. So December is right around when that rookie wall would hit.
Except Chiefs rookie CB Marcus Peters is not hitting that wall. He saw the wall and blew past it without stopping because he is getting better as the season goes on.
Marcus Peters before the bye: 60.7% comp, 7 TDs 3 INTs, 101.7 rating. Post bye: 41.4% comp, 0 TDs, 5 INTs, 25.7 passer rating allowed.— Pro Football Focus (@PFF) December 28, 2015
The Chiefs have had eight games before the bye and seven games after the bye so it's a decent sample size. I can't think of anything better than seeing your rookie get better with more reps, especially at that position which requires a short memory. Peters looked like a pro from his very first play in the league (an interception in Houston) so it's fitting that he's like a veteran who knows how to handle the grind of a season. His football smarts are what surprised me when he came to KC. He looks like the smartest player on the field.