There's a fascinating thread at Clarkesworld Magazine people should read, where editor Neil Clarke comments about submissions. According to Neil, out of the last 4180 submissions they received, their acceptance rate averaged around 1 in 350 submitted stories.
What fascinates me is Neil stating that "near misses" (which I take to mean submissions that almost made the cut) number about 1 in 35. That means for Clarkesworld, out of every 350 submissions there is one acceptance and 10 near misses. Everything else didn't have a chance in hell for some reason, be it bad writing, bad plots, wrong story for the wrong market, and so on.
It's often said that submitting fiction is a numbers game, and this proves it. But these numbers likewise show that if you write a great or very good story which meets the guidelines for a particular market, you actually have decent odds. Because what these numbers tell me is that the vast majority of submitters to Clarkesworld have no chance of landing an acceptance or a near miss. Instead, they are so out of the ballpark that they aren't even competing in the same game as the writers Clarkesworld usually publishes. And based on my editing experience, this is probably true with most magazines.