Traditionally, skill related fitness was only achieved by practicing one's sport or activity. Traditional training methods focused on the five components of fitness (muscular strength & endurance - cardiovascular fitness - flexibility - body comp) and left the skilling activities to be accomplished while at practice.
Functional training strategies now take advantage of integrating skilling activities within training sessions. The difference from skilling activities in training programs versus on the field skills is that on the field skills work very precise moves and have narrow scopes. This can leave athletes vulnerable to injury when they are put in an odd and unpredictable position/action on the field. Whereas, functional training looks to also work within the scope of the sport, but to increase one's thresholds past the perceived need on the field. Skilling fundamentals can include balance, jumping, hopping, pivoting, lunging. When these fundamental skills are enhanced an individual can improve speed, agility, coordination, endurance, mobility, strength & power. Most importantly, properly progressed skilling activities can keep an athlete on the field - not in the training room.