There's no doubt that competition--when kept in context--can significantly enhance your ability to do the real deal when you need to. Competition teaches the ability to focus and perform under pressure--sometimes intense pressure. You learn a lot about yourself and your teammates through competition that I feel has direct bearing on how you perform under real combat.
Least in my experience it did.
Trust me...you want the guys with the drive to win on your side when the real thing goes down. Mindset, and the proven ability to focus and perform under pressure will beat the best trained quitters in the world every day. I believe that with all my heart.
“Est Nulla Via Invia Virute”