"Heart" in MMA is almost as useless as the "heart" power was in Captain Planet.
Almost as useless.
Fans make a big deal about heart—a trait which is generally ascribed to fighters who get hit a lot yet still stay conscious and in the fight. They say, "Woah, that guy just got beaten bloody for 15 minutes without succumbing to his injuries! What heart" or things of that nature.
To fans, heart is something valuable.
And, to be sure, it is valuable to an extent. Heart keeps a fighter in the fight when it's not going their way so that they could potentially come back and win. Heart leads to stunning comebacks like Tim Boetsch vs. Yushin Okami and Frankie Edgar vs. Gray Maynard III.
However, for every Boetsch-Okami or Edgar-Maynard III, there are many other fights where heart amounts to naught but increased head trauma—it doesn't win the fight, it just prolongs an inevitable loss and exposes the fighter to more pain and punishment.
Fighters walk forward (or backward as the case may be) while continuously taking punishment, zombified, while the crowds go nuts and the h-word appears in spades in tweets and comments and forum posts across the Internet.
There are countless examples of this but a more recent one is Junior Dos Santos vs. Roy "Big Country" Nelson. Dos Santos is one of the most acclaimed power-punchers in MMA, yet Nelson managed to withstand his barrage for a full 15 minutes without being knocked out.
As a result of surviving such brutality, Nelson and other fighters who have been in that situation absorbed the love and respect of the crowd—but they also absorbed dozens of hard blows to the head.
Should we really be cheering and encouraging that and saying that it's admirable?
It is the fight business, sure, but there's a difference between athletic competition and senseless injury and violence.
Thus, might it not be better if we give as much adulation to fighters who employ strategies that don't require their heads to be veritable punching bags or fighters that emphasize proper defensive techniques rather than the "stand and bang" doctrine?
Yes, such tactics might not be as exciting, but they're certainly better for the fighters and ultimately better for the future of the sport.