One aspect of the draft that many might not think about, however, is the salary cap and how much the rookies might factor into that. Thankfully, Jason Fitzgerald of Over the Cap put together a great article looking at the rookie salary cap and explaining how it works. Wrote Fitzgerald:
During the offseason NFL roster expand to 90 players and only the top 51 players count against the salary cap. Every rookie that is signed will either replace a player currently in the top 51 or not count enough against the cap to be in the top 51, in which case only their prorated bonus money will count against the cap. This is why it is important to understand the concept of effective cap space.
In other words, here's the deal: the Colts wouldn't have to come up with all of that cap space right away, as instead many of the rookies would likely slide right in near the end of the top 51, while regardless one of the bottom salaries will be dropped. So, for instance, if a rookie signed for $2.5 million and the last guy of the top 51 was under contract for $500,000, the Colts would need only $2 million in salary cap space versus $2.5 million. That's the general idea.
With that in mind, let's plug in real numbers for the Colts. The Colts have nine picks in the 2015 draft, including at least one in every round. Fitzgerald projects the Colts to have a total rookie pool number of $5,386,895 among the nine players, which initially seems like quite a high number. In reality, however, their effective cap cost for these rookies will only be around $1,471,895. That's the number that the Colts are projected to need to sign their rookies, which is a much different number than the one upwards of $5 million, meaning that the Colts won't need as much cap room to sign their draft class as many might have thought.