It is basically sacrificing your self for a win. Think mj with the flu. And ct mkg has the it. He just does what he has to to win. BaRnes had the it last year but has lost it.
The last game I watched of MKG's was against Vandy. He was completely shutdown by not being guarded, and didn't really see him shut anyone down on the other end. I just don't see how someone who can be ignored until he crosses the FT line can have "it" as a SF (unless their defense is truly amazing, I don't see that from MKG, I see opponents scared to drive it into the pit of doom that is Anthony Davis's paint).
His 3pt % along with his FG % continue to drop each week as teams are figuring out "Hey, we don't have to guard this guy at all". I like his rebounding a lot, and his defensive play, but those don't outweigh his flaws.
His ceiling is Shawn Marion. I doubt he will ever be able to reach that ceiling unless he is put in the right system (Mike Dantoni era Suns style).