Show Your Hand was where it all began for the Average White Band, which turned out to be one of the hottest funk/soul outfits of the mid- to late '70s. But when MCA released this debut LP in 1973, the band's commercial success was still a year away - it wasn't until they joined the Atlantic roster in 1974 that they exploded commercially. Show Your Hand, in fact, was among 1973's neglected R&B releases. In retrospect, it's easy to point the finger at MCA and say, "You dropped the ball; this album should have done better." Atlantic successfully broke AWB in 1974, so why weren't MCA's promotions and marketing people able to accomplish that the previous year? But in all fairness to MCA, breaking AWB was a challenge - imagine trying to convince '70s soul stations that a white band from Scotland played first-class funk and soul…