I've read about that (the bad goals given away, especially in that WC) - but as with anything with Yashin - I've only really read about it.
I'm basing my opinion more on how he revolutionized the position, similar to (for example) how Santiago Bernabeu forever changed the club scene after assembling the Madrid team from 55 onwards, not just Di Stefano, but Puskas and Kopa as well (to go with the always overlooked Paco Gento etc.).
Nothing was the same after that.
That said...
I do admit my own potential lack of information on games pre-1990, because everything until then
I've only ever read about, seen on tape (a select few games, nothing more) or seen some highlights.
I'm very vary of "passing judgement" on all that - but I always wondered why a lot of people weren't. Not just here, everywhere.
(doesn't apply only to hockey, I marveled at so many threads on here comparing Eddie Shore to Lidstrom, when absolutely noone here has seen him play)
Nothing compares to actually watching games, and for a vast majority of people that doesn't help either.
Most football fans (most of my own friends included - some of which played high level football in youth systems) - either don't care enough to understand what makes a great footballer in a certain position, or simply don't know enough.
Never stopped them from making criticisms though.