Four rookie quarterbacks have gained starting jobs this NFL season: Oakland's Derek Carr, Jacksonville's Blake Bortles, Minnesota's Teddy Bridgewater and Tennessee's Zach Mettenberger. I would caution right at the outset here that the sample size we have on each of those four QBs is too small to be making any determining judgments, but what we've seen in their statistics and on-field performance can tell us something.

As an evaluator of an NFL team that is starting a rookie quarterback, you aren't expecting too much, to be very honest. What you're hoping to see is improvement from start to finish, in two key areas:

Mechanics: This includes foot placement, arm placement, delivery and weight transfer. But perhaps most importantly, it involves how well a rookie QB does at maintaining his mechanics over the course of the season after he's taken a lot of hits, because rookie QBs are going to be hit a lot more than veteran QBs. The excess hits are the product of two factors: They don't know how to get the ball out as quickly, and defenses will blitz them a lot more to create confusion and turnovers.

How they handle themselves: How do they command the huddle? How do they handle being under duress? How do they conduct themselves as professionals? How do they bounce back from failure?

What you're looking to be able to say at the end of the season is that the arrow is pointing up and that a rookie QB is progressing physically and mentally -- even if it's only a little bit. Your rookie quarterback can have a rough year statistically -- and most of the time he will -- but you want to see that he got better as the season went on.

Here are a few of my thoughts on the four rookie quarterbacks mentioned above, followed by a look at the next steps in the development process of a young QB.

Carr

Derek Carr, Oakland Raiders

The first thing that many will notice about Carr is that he has the arm to make all the NFL throws, but what has also stood out to me this year has been his leadership. He hasn't been flustered when things have gone wrong, and let's face it, many, many things have gone wrong for the 0-10 Raiders.