As a writer, I absolutely LOVED all the alliteration in this episode - they were searching for an Eastern European with a strange accent and Castle kept making guesses about an Elusive Estonian, a Mysterious Moldavian, a Suspicious Serbian and several other Baltic states !! So much fun!! And the poker scene where they honor their "fallen" colleague - hysterical :)
"The Dead Pool" is yet another disappointing episode of Castle. They resorted to the tired old cliche of issues with an athlete possibly juicing and someone wanting to hold him down. Just got a huge feeling of "been there, done that" while watching this episode. The way things turned out felt as old and hackneyed as the plot itself and there was another really boring "moment" between Castle and Beckett to close things out. They have achieved that "tension" between those two they were seeking awhile ago, but with each of these scenes they seem to make me want to see something between those two less and less.
Castle is continuing its downward spiral into becoming a generic procedural. Maybe the early renewal hurt the show creatively.