OKAY I did some research, I wasn't completely paying attention because I was listening to baseball in the background.
But I think it wouldn't affect the cap space. I have a few links and steps.
1) But, to answer your question, Roberts rookie contract is under the "Total Rookie Compensation Pool", which I found from this link:
http://salarycap101.net/2) Than I went to another link
http://overthecap.com/explaining-the-nf ... alary-cap/ and saw this this, "The “Rookie Pool” is a cap within the salary cap. It is essentially money that your team needs to place aside for your rookies. It is not added to your salary cap at all." I wasn't 100% sure, thinking that writer was referring to just the 1st year rookies as he was talking about Alex Smith etc.
3) So I went to this link
http://russellstreetreport.com/cap-faqs/ ""Cap within a Cap” because while it operates as a cap on what teams can spend on their rookies, it does not have a dollar for dollar impact on the team’s overall Salary Cap. Because of this, when you hear that a team has a $4.5M “Rookie Cap”, that doesn’t mean that the team needs $4.5M in overall Salary Cap space. "
4) Lastly, the previous link led me to this for further explanation
http://russellstreetreport.com/An-Expla ... ally-Work/"The Rookie Cap is not a separate, distinct pool, but rather, a separate calculation and there is not a dollar-for-dollar correlation between the Rookie Cap and the overall Cap. So, while all of the Salary Cap numbers of a team’s draft picks must fit under the team’s Rookie Salary Cap, very rarely will all of that amount actually impact the team’s overall Salary Cap."
"For Salary Cap purposes, the bonus received by the player is prorated over the four years of the deal and that prorated amount is added to the base salary to create the player’s Cap number."
Even though, this is referring to players who aren't good enough to make the team and get cut I guess it could work for exceptional players no argument aside "As such, under the Rule of 51, those players’ base salaries of $420K will not count against the teams overall Salary Cap and only the player’s bonus proration will count toward the team’s overall Cap."
In one of the links it showed that a player can be under this rookie compensation pool for his whole career and gives the minimum for each year. And I'd assume he would never affect a teams cap space.
Feel free to do some research and comment if I missed anything!