Under the rules, any team "losing more or better compensatory free agents than it acquires" is eligible for compensatory draft picks.
Compensatory free agents are determined "by a formula based on salary, playing time and postseason honors," according to the NFL. It does not include every free agent lost or signed by a team.
The Giants and Colts each received a compensatory pick despite not suffering a net loss of compensatory free agents last year. Under the formula, the free agents lost by the Giants were ranked higher than the ones signed due to a specified point differential based upon salary and performance.
So Jerry Reese will have one more late pick to play with in April. Of course, Reese signed one of the free agents he lost last year when Ross opted to return and sign a one-year deal with the Giants last week.