As my dad loved to say about
Berra's propensity to swing at bad pitches,
"Yogi never saw a pitch out of the strike zone he didn't like." 
People seem to be mixing up the terms
"appreciated" and
"valuable."
Yogi is greatly appreciated by baseball fans, it just doesn't happen to translate into bigger prices for his cards, which is quite nice for us buyers, but not so much for sellers.
There has always been a
huuuuuuuuge amount of appreciation for him as a player and a highly-engaging person.
He's not
underappreciated, his cards just happen to be
undervaluable.
