Boxing's lack of central 'branding' makes it far harder for casual fans to follow.

You can like NFL football without knowing more than one or two players. You might not even know every team. You just know that you've seen it before and it was exciting. If there is an NFL game on, you know that you are seeing the best level of american football available. If its sunday afternoon or monday night, there is a game on. If its the superbowl, you know its 'the big game'. Plenty of people watch who couldn't name ever team, let alone 2 players/team.

Compare this with how difficult it is to follow boxing. If you knew, lets say 15 fighters, you'd still have a tough time knowing what you were looking at on most televised cards. You also probably don't know when those televised cards are. Even if there is a belt on the line, you can judge that the guys must be pretty good, but some belts mean less then others and some weight classes seem weaker then others. For casual fans, they don't know what's happening.

The UFC closes a lot of this gap. There are fans who might only know 5-10 fighters, and many 'fans' couldn't even list the 5 UFC beltholders if you asked them. They don't know what weight class half the fighters are in. I've sat in bars beside ecstatic fans telling me they'd like to see GSP fight Rashad Evans, and seem to not really pick up on my subtle hint that the 35 lb two weight class differential is a fair bit. But fans like this can sort of follow the UFC. Every 3-4 weeks there is a PPV card. You like UFC, you watch that, the end. If there's a belt on the line, its a 'real' belt.

The last time Wlad Klitschko fought, it was on free tv here, late afternoon. I have friends who like boxing, but don't follow it well. None of them knew the fight was even on.