DC's "mistake" (I have oft heard opined) is that they rebooted some series post-Crisis but not all. I disagree with that assertion (for a couple of reasons), not the least of which is I don't believe the way they handled it was a mistake. Before I start my examination of the post-Crisis Superman in particular, I'd like to briefly touch upon how the Crisis on Infinite Earths affected certain key titles, starting with...
SUPERMAN: John Byrne's Superman reboot was certainly the highest profile one, even making the cover of TIME magazine, but I think it was a "soft reboot" at best, at least that's how it was pitched, although it did become a hard reboot eventually.
(Incidentally, the "HE'S 50!" blurb was much more impressive to me in 1986 than it is today.)
Superman was given a new origin, but the modern DC universe had been "10 years old" pre-Crisis, and it was still 10 years old post-Crisis. The Man of Steel limited series covered that gap between Superman's first appearance in issue #1 and the new Superman #1 during which all of the previously told Superman stories were supposed to have occurred. Theoretically, a reader could go from the pre-Crisis Superman #422 to the post-Crisis Superman #1 (discounting Alan Moore's out-of-continuity "Whatever Happened to the Man of Tomorrow") without missing a beat, although eventually the pre-Crisis stories were rendered "out of continuity" by newer ones.
BATMAN: "Batman: Year One" (Batman #404-407) represents what I call a "fuzzy reboot" in that he, too, was given a new origin, but this one replaced earlier continuity more quickly. Crisis really had no effect on Batman continuity... until "Batman: Year One" (which was not only post-Crisis, but post-Legends). Immediately thereafter, Batman became Batman: The New Adventures (with #408), starting with a new origin for the Jason Todd Robin.
Gone was Jason Todd's circus origin, replaced with a new "street urchin" origin. Does this mean the pre-Crisis Jason Todd stories still "happened," mentally substituting one origin for the other? Or did the "New Adventures" origin wipe the previous (blond) Jason Todd stories completely from continuity? That's why I think of "The New Adventures" (more so than "Batman: Year One") as a "fuzzy" reboot. It soon became a moot point as the character was dead by #429.
WONDER WOMAN: Wonder Woman is the only example of a "hard reboot," wiping from continuity as it does all previous 329 issues. What makes matters slightly more problematical is that Wonder woman's origin did not take place "ten years ago," but rather she made her first appearance in "man's world" circa the post-Crisis mini-series Legends.
JUSTICE LEAGUE OF AMERICA: You'd think removing Wonder Woman as a charter member of the JLA would be problematical, but it wasn't, really (YMMV). All that was needed was to replace Wonder Woman with Black Canary (and if you think BC couldn't possibly replace WW, it's been too long since you read those early Silver Age JLA stories). All that's required is a slight "mental rewrite" as shown in Secret Origins #32.
But again, all this has been rendered moot by subsequent revisions which have alternately restored and removed Wonder Woman's status as a founding member. (I couldn't even tell you what it is now.) If anything, in a way Crisis strengthened the JLA's place in continuity. As individual pre-Crisis Superman and Batman stories were systematically carved out of DC continuity, the JLA stories in which Supes and Bats participated still "happened."
LEGION OF SUPER-HEROES: Here too, as with Wonder Woman's removal from the JLA, you might think that the removal of Superman's career as Superboy from continuity entirely might prove problematical, but again I assert that it was not (and again, YMMV). Honestly, the "pocket universe" explanation was and remains one of my favorite stories from the immediate post-Crisis era, and even helps to cement those Silver Age Adventure Comics stories that much more firmly in DC continuity. And (also "again"), the question has since been rendered moot by so many revisions that I no longer know what's "officially" considered to be in continuity and what is not.
NEXT: John Byrne's 1986 Man of Steel limited series.