To be honest I don’t know that a lot of past players have had their reputations rise all that much due to better understanding of how baseball works. Maybe among people really into sabermetrics, but that’s a small group.
Certainly, some players have had their reputations fall. A lot of the Hall of Fame’s more awful selections, like George Kelly or Freddie Lindstrom, are now properly regarded as bad selections.
But I don’t think that has a lot to do with newfangled stats like WARP and OPS. I think the really big change in that regard has just been the availability of information. When I was kid - and we’re just talking 25 years ago or so - getting detailed baseball information was hard. There was no Internet, no 24-hour sports coverage on multiple channels, and spotty reporting of stats in newspapers. So if they said George Kelly was a Hall of Famer, you kind of had to assume he must have been pretty awesome. It wasn’t possible to instantly to a web site with hyperlinked details on every player who’s ever played and say “Hey, you know, there are lots and lots of guys just as good as this guy.”
I can think, though, of one player who might have had his reputation really soar; Richie Ashburn. Ashburn was already regarded as a pretty good player but his reputation started to really climb in the 1990s based on two things:
- Increased understanding of the importance of on base percentage, which was most of Ashburn’s offensive game, and
- Range factors.
Ashburn, of course, made absolutely ludicrous numbers of plays, amazing numbers. When “Range factor” came into vogue it made Ashburn appear as if he was the greatest defensive center fielder who ever put on a glove. People started saying that Ashburn was a forgotten defensive genius who won many, many games with his glove. And I think that, plus the understanding of his on base percentage, helped get him into the Hall of Fame (his broadcasting career helped, too.)
The funny thing is that the range factor thing was, of course, wrong. Ashburn’s huge number of putouts was to a large extent a product of circumstance; he happened to play behind some of the most fly-ball prone pitching staffs of all time in a park that allowed for a lot of fly balls. He was an excellent center fielder all the same but he was more like Vernon Wells, not Willie Mays. The assessment of a LOT of fielders based on the analysis of that time was, in fact, hopelessly wrong and based on a lot of incomplete information. The assessment of Ashburn at the time he was playing - that he was very good but not great - was closer to the truth than the amazed declarations of the 1990s that he was the greater center fielder to ever live.
Ashburn isn’t by any means a bad Hall of Fame choice like Jesse Haines, but I think he’s the answer to your question; he was below the line before sabermetrics and sabermetrics helped him get over it.