Joeygee0531 described the stereotypical call of Baseball announcing. When good 'ol Joe Nuxall was announcing for the Reds, there would sometimes be a whole minute going by without anything but crowd noise. Loved it! If you don't like baseball, no matter how good the announcer is, it won't make a difference. What a GOOD announcer does is draw you a word picture. Lets you know where everyone is, what they are doing, if they have time at a long at bat quite a bit of background. If you are NOT INTERESTED in the sport, nothing anyone can say or do will influence your appreciation of just how hard announcing baseball WELL is. But as a sport, the pacing and spacing of baseball is what makes it great for radio. I prefer to LISTEN to a game than watch it. The depth of the imagery provided by a good radio announcer is better than the highest definition picture broadcast on TV!
NASCAR announcers do a great job trying to follow the action, but at times it is just impossible to "see" the race through the radio. There simply isn't time to get an adequate word picture drawn. You really have no idea what is going on during starts, restarts, pit-races, etc. They really give it a go and in general I think it couldn't be done any better, but it doesn't lend itself to radio.
Football can also be good on radio, but as usual it depends on the announcer. Again there isn't enough time for the announcer to draw the picture of everything that is happening during a single play most of the time, but the gaps between the plays can and is usually used to fill in the sketch the announcer made during the play. The actual call of the play is very basic, but what sets announcers apart is how they fill in those gaps.
Hockey on the other hand is very difficult for me to follow on the radio. The game moves very fast while "nothing" is happening. By nothing here I mean the puck is being fought for in a very good game by both teams between the blue lines. The announcers keep up very well, but the game just moves too fast for them to adequately tell you who is where, what they are doing and what is actually happening.
I do not care for basketball so just like some here and baseball, I do not like it on the radio, but that is not because I think it's "the worst sport on Radio". I just don't like the sport (NBA) in general. I do listen to NCAA (Univ. of Cinci and XU as well as some high school). I think the game suffers from the same problem as hockey most of the time and the announcers just don't have the time to draw that word picture.
One of my favorite quotes from "The West Wing"
See ya
Tony