Any halfway serious fan of baseball should know about it, but it's not something I'd go around asking as a litmus test or anything.It happened over 100 years ago and unless you are a hardcore fan of the Cubs and/or the Giants (or of baseball in general), it's understandable to not know about that play.
Felger is an easy one to give a pass to on this topic. Mazz, as a guy who has primarily been a baseball reporter, gets less of one but still, it's not really something that every baseball fan or reporter should know about off the top of their head.
A fucking baseball reporter should damn well know about it.