One key element that McCoy had, that neither Swoopes or Heard have, is the benefit of is having a football coach for a dad. Colt had years of training on reading defenses and how to lead a team.
Colt also had the huge benefit of some tremendous playmakers at receiver. Colt had a noticably weak arm until the end of his career, and Cosby, Shipley, and Charles delivered YAC that turned short dinks into sizable gains. In 2007, Finley turned 2 end zone INTs into TDs by pulling misfires out of the hands of DBs (Baylor, ISU).
In contrast in the spring game, WRs failed to bring down 2 TDs Swoopes hit them in the hands with, and dropped another long completion that would've been in scoring position. And, there's no Jermichael Finley at TE to turn INTs into TDs.