ATDTDA (17): "Poker" Metaphor Analysis (pp. 474 - 75)

[Tim Strzechowski]

"What he didn't quite see was how little it mattered to her by now.  If the marriage was coming more and more to resemble a kitchen-table poker game, why, she valued her forgiveness at not much more than some medium-size chip.  She had allowed the immediacy of Webb's death -- Webb's life -- to pass like smoke into the steadily darkening air between them.  From a thousand small tells he had remained too unschooled in deceit to know how to keep from letting slip, Lake in fact already knew, or suspected too much by now not to know.  But it would have to be Deuce who turned all the cards face up.  And the day, before they knew it, had accelerated upon them, avalanche style" (p. 474).
 
 
Really good writers, we'd hopefully agree, choose their metaphors carefully.  What makes this metaphor so effective in this section, given the events here?  In what ways does poker imagery (and sustaining a poker metaphor) "work" here?