It also helps when you aren't playing the same map over and over and over again. Sports (and MOBA's/RTS's) don't have to deal with it since everyone plays on a standard field, but video games are different. It's pretty boring to watch Map X for the 50th time using the same strat as the majority of teams use. It's not the strats fault, it's just that we need more maps for competitive play.
I'll be honest, I've stopped watching TF2 comp because I know just about everything Team X and Team Y is going to do, and that Team X will beat Team Y unless someone chokes. When I first started watching, everything was new and it kept me interested, but now, it's just 'Oh, that team is going to win, they'll most likely do this and that etc.', I have no reason to watch or pay attention to the game I once watched/played 24/7, the game where I would jump into mumble with some broski's and watch 6's together and get hype.
When I see a new/dynamic map, it interests me because the players aren't going to always do a certain strat or will make up weird/interesting strats that I want to see the outcome off. Like pulling off the Wildcat in Handegg, you never know what will happen with that, even though it's the same formation, something is going to surprise you. We need more maps like that, a map that is almost impossible to have a set number of strats that constantly work. PL_Swiftwater is a perfect example. It's not the best map, but there is always a new way to play it. It is they most dynamic PL map that is in comp, and while it could use some work (mainly with point 3), it's always interesting. What's worse is that 6's doesn't do PL, so they have Gpit as the most 'dynamic', and even then it's either Ironman or hold B.
Comp TF2 needs more of that in general, otherwise it bores me now. The only thing that interests me these days is Plat HL and only because teams change so much, so you never really know what will happen. Also note that you are trying to pull people in that like actually playing video games, so if you aren't interesting them, they won't come ever. As much as I liked DJC's casting, he wouldn't 'save' TF2 comp scene, he would just prolong it's death.
In short, we need to find good map makers who want to make maps for comp TF2 that aren't bland and help them by playing on them and giving good feedback otherwise TF2 is just going to slowly die.
But don't get too down, I'm sure a good number of people who stopped watching are now playing in comp. It just has to have that new car smell. Just the thoughts of someone that went from watching to watching and playing to playing a little to probably quitting/quitting to make maps.
Words.