One thing I've often suspected, but have no way of verifying, is that ice hockey is the hardest sport to announce (that is, do play-by-play) on television. It's fast, chaotic, and the players are swathed in padding that makes them all look identical. Sometimes watching a hockey game I'm blown away at the ability of the announcers to even keep up with the action, much less give informative commentary.
Am I right? On the one hand, I have absolutely no experience broadcasting anything and thus all of my opinions are ignorant. On the other hand, this is the internet -- so why should lack of experience and utter ignorance stop me?
So, with all that in mind, I've created a four-part rubric to gauge announcing difficulty (each element on a five point scale).
1) Chaos: How fast does the action happen? How ordered or disordered is it? Sports which are highly position-oriented might be fast-paced but you pretty much know where everyone is going to be (i.e., the quarterback will, for the most part, always be doing quarterback-y things). Other sports are more free-for-all.
2) Density: How many "announceable actions per minute" are there? Some sports are densely-packed with "things" that need to be announced (i.e., each time there's a pass, you pretty much need to say who the pass was to and from). Others are more leisurely.
3) Spread: How many different things are happening at the same time? In a boxing match, you can pretty much concentrate on what's going on in one spot -- where the boxers are fighting (note how there might be very dense action in a boxing match that's not at all spread out). In a football game, different announceable things may be happening all across the field simultaneously.
4) Opaqueness: How much of what's going on is pretty much intuitive to anyone with a basic understanding of the game, and how much needs explanation? Are there deep rule interpretations that need to be explained on the fly, or is everything pretty much as it appears on face?
I'm not including in my metric difficulties associated with making the sport interesting. Perhaps it's really hard to craft a gripping narrative about golf, but if that was part of the criteria then the most boring sport would be the hardest. I also assume that the announcer has a solid grasp of the sport he or she is broadcasting, and an audience which has basic familiarity with the rules of the game.
Okay -- without further delay:
The reason I think hockey is the most difficult is because the game moves so damn fast. Players are constantly passing and checking and shooting and crashing into each other. And while hockey has positions, outside the goalie any player can pretty much be anywhere at any time. To be able to pick up (underneath layers of padding) that it was Jon Smith who leveled that check in the corner in the approximately .5 seconds you have to react before having to announce who retrieved the loose puck and centered it.... is a task that seems positively titanic.
Chaos: 5, Density: 5, Spread: 3.5, Opaqueness: 2.5. Total: 16
The rules in football are often pretty hard to follow (what makes "holding" different from anything else the defense does?). It's a relatively spread out game, and as the play develops there's a lot to call, but soon the action pretty much converges and it gets a lot simpler. Plus you get lots of long breaks between plays.
Chaos: 2.5, Density: 2.5, Spread: 4, Opaqueness, 3. Total: 12
From an announcing standpoint, it's like slower hockey. Plenty of passing and movement, but not done with the rapidity of a hockey game (and you can see everyone's faces, which helps). Hard to truly appraise penalties when everyone is flopping all the time.
Chaos: 2.5, Density: 2.5, Spread: 3.5, Opaqueness: 2.5. Total: 11
Very similar to soccer. It's a little faster, but also a bit more compact (the larger field size in soccer means you have to keep an eye on more things).
Chaos: 2.5, Density: 3, Spread: 3, Opaqueness: 2. Total: 10.5
One thing to focus on, but that thing can get hectic in a hurry. Boxing also seems to have more than its share of bizarre moments, though for the most part it's pretty intuitive that the person getting beaten up is losing.
Chaos: 2, Density: 3, Spread: 1, Opaqueness: 2. Total: 8
Gymnastics and Figure Skating
I think these have the exact same issues for an announcer. They're pretty slow, you've got time to breathe between announceable actions, but the major problem is that outside blatantly obvious falls and flops no lay person can tell what's intentional and what's a mistake. A figure skating announcer could tell me literally anything about the average routine -- from "it's the most dazzling performance the Olympics has seen in decades" to "most middle schoolers could handle this" -- and I'd believe them.
Chaos: 1, Density: 1.5, Spread: 1, Opaqueness: 4.5. Total: 8
Another relatively straight-forward sport, albeit one that moves pretty fast.
Chaos: 2, Density: 2, Spread: 1, Opaqueness: 1.5. Total: 6.5
Slow-paced, rigidly position-oriented -- people are always pretty much where you expect them to be -- and only occasional need to pay attention to more than one thing at a time (tagging up runners, stolen bases). Baseball also has a couple truly weird rules that come up more than you'd think (infield fly rule, balks).
Chaos: 1, Density: 1, Spread: 1.5, Opaqueness: 1.5. Total: 5
One thing happens: a player hits a shot. You talk about it as it soars through the air, until it lands. If it's closer to the hole, that's usually good. Further, bad. Some very obvious traps are also bad. Repeat.
Chaos: 1, Density: 1, Spread: 1, Opaqueness: 1. Total: 4
Not rated: Rugby, Lacrosse. These are two sports that in particular I can imagine being quite difficult to announce, but I don't know enough about them to say for sure.