How much money *should* Tom Brady be paid? What are the appropriate cap figures for Tony Romo and Darrelle Revis? This series looks to derive the appropriate salary cap value for each player in the NFL.

Let’s start with the basics, which will include many generalities and rough estimates. I have chosen to ignore all players who are in the first three years of their rookie contracts; while we could try to determine the “fair market” cap values for Andrew Luck, Robert Griffin III and J.J. Watt, that would be nothing more than an academic exercise because their 2013 salary cap figures are set in stone. Instead, my goal is to determine the appropriate salary cap values for NFL Veterans (in this post, “Veterans” means all players with at least three prior years of NFL experience).

Note that ALL of the numbers in this post can be manipulated by each user thanks to the Salary Cap Calculator below. Your opinions regarding my assumptions should not interfere with your use of the salary cap calculator.

The salary cap in 2013 is $123.9M, but because players on injured reserve count against the cap, a buffer is needed to sign healthy players during the season. On average, each team will have placed on their roster 64 different players. Some of those players will be signed during the year and may only be on the team for a few weeks, so they won’t cost a significant percentage of the cap. On the other hand, a couple of players are usually on IR before the season even starts. Let’s assume that teams should spend 96% of their cap dollars on the healthy 53 players on their week 1 roster. The next step is figuring out how many of those salary cap dollars will go to non-Veterans.

Thanks to Overthecap.com, we can determine the percentage of the salary cap allotted to rookies, second-year, and third-year players on their first contracts with the teams that drafted them. For 2013, Jason Fitzgerald (the site’s owner) projects the 256 draft picks to cost the average team $5,617,710 in cap dollars. Based on last year’s draft numbers, the 256 ((To make it apples to apples, I added three extra players at $491,474 cap hits, since there were 253 draft picks in 2012 and 256 in 2013)) second-year players from the 2012 draft should count for $6,706,038 per team against the 2013 cap. For third-year players we will need to estimate because the data isn’t easily available. Players drafted in 2011 are projected to make about 2.5% more in 2013 than they did in 2012, so if we take a 2.5% haircut off of the amount Jason projects third-year players to make in 2014 (numbers that are easily-available), we can estimate that third-year players in 2013 will cost about $7,741,296 this year.

The problem with those cap figures is that they assume all 256 draft picks make week 1 rosters, which we know is not true. On the other hand, there are many undrafted rookies, second, and third-year players on extremely cheap deals ($416K is the minimum for 2013 rookies) who will wind up on rosters. So how can we get a more precise picture of how non-Veterans affect the salary cap?

I looked at all rosters from 2004 to 2012. On average, there are about 202 drafted rookies, 166 drafted second-year players, and 136 drafted third-year players on their initial contracts at any one time, a total that represents one-quarter of the players in the league. There are also about 413 undrafted players in their first three years in the league each season, and another 89 players in their first three years that were drafted but now are on new teams (like the other Robert Griffin from Baylor).

So how does that change the analysis from above? Instead of 256 rookies in the NFL costing each team $5.6M, we should project only 202 of the draft picks to make 53-man rosters. Most of the cuts will be limited to late round picks, so the effect won’t be proportional. I’m going to make a gut guess — which you can freely change yourself — and say 87% of the cap dollars will go to those 202 players, enabling us to peg 2013 rookies at $4,887,408 per team.

Again, using nothing more than my a crude estimate — which you can freely change in the calculator below — I’ll put the 166 second-year players at 77% of the salary cap value for all 256 picks, which means $5,163,649 per team. For third-year players, I’ll guesstimate that about two-thirds of the salary cap value is tied up in the 53% of the players that actually remain on their rookie contracts in year three, which would have those players occupying about $5,109,255 of cap space.

From 2004 to 2012, there were, on average, 16 players per team who were in their first three years and were not drafted by that team. The minimum for a second-year player will be $510K for 2013, so that seems like a fine enough estimate to use here. And while the majority of the 9 to 11 players added by a team to cover injuries will consist of these players, remember that those players added after week 1 are irrelevant to the point of this post (which is how much money should be spent on the opening day roster — hence the need for a buffer).

The good news is we’re almost done. Each team will roster 6.3 rookies, 5.2 second-year players, and 4.3 third-year players that they have drafted, which means they’ll have a total of 15.75 players on their rookie contracts. Let’s say each team will place 1.75 players on IR before the season, to give us a round number of 39 remaining spots. Of the 16 undrafted/second-contract players in their first, second, and third years, perhaps 9 of them will be on the healthy opening day roster. That means the other 30 players will be Veterans in their fourth year or later (and we can assume two more Veterans will be added during the season to total 64 players). The minimum amount for Veterans varies based on experience, but we can use $850K as a rough guess for the average salary cap minimum for the group of Veterans as a whole.

You can play with the Salary Cap Calculator below to see why, but all of the above leaves us with about about $74 million marginal dollars to spend on our 30 veterans. That’s about 2.45 million marginal dollars for each Veteran, or about $3.3M per player. Now, think back to the thought experiments from Friday and Saturday. If you decide that the replacement-level team boosted by young players from the thought experiments would win about 3 games per season, then the marginal value of a win is about $15M. That’s because the average team wins 8 games, so if a team full of players on veterans minimum contracts and young players will win three games, then the $74M marginal salary cap dollars you will actually spend on Veterans only nets you five wins. That’s about one win for every additional $15M you spend. If you think such a hypothetical team will go 1-15 on average, then a player that can get you one marginal win is only worth $10.5M in cap space. The more productive replacement-level players are, the higher the value attached to the league’s stars.

With so many estimates in this post, I think the most valuable part (aside from the thought experiment) is the Salary Cap Calculator below. You’re free to change the inputs as you like, and the Calculator will automatically update. I’ve included a field for dead money, although I’m not quite sure how — or if — that’s a variable that should factor into this analysis.

That is a lot to digest. Let me know your thoughts in the comments. This is only step one in the process, and reader feedback will have a big role in how the rest of this series turns out.