Spence was a better win than a weight drained Garcia and Bud`s performance v Spence was far better than Tank`s v Garcia.
Neither one is underrated IMO. Bud is recognized as being among the most skillful boxers on the planet right now, high up in most p4p lists, and even people that aren't fans of his style or personality readily admit that being an undefeated three (soon perhaps to be four) division world champion he's a first ballot Hall of Famer. He's rated exacty as he ought to be. Tank if anything is overrated. For a supposed heir apparent to Floyd Mayweather Jr. his technique is pretty trash, and when you get down to it he relies on his power to bail him out whenever the going is getting rough.
Crawford is rated highly with good reason. Tank is overrated for what he's achieved, and who he's ducked. Neither is underrated, but as Tanks the more overrated of the two by a decent way, one has to answer Crawford.
Who do you like in a possible Loma-Tank showdown, IB? While I think it's a very dangerous fight, given his opponent's obvious advantage in power, I think Lomachenko can out point Tank over 12, particularly if he boxes for points rather than punishment and limits the exchanges (not as if Tank is a high output guy anyway).