This will be a quick take, so just be aware of that. With Craig Calcaterra at Hardball Talk's rumor that the Rangers and Astros are "getting close" to an agreement with the Astros about Roy, it's time to take this seriously - no matter what Buster Olney says.
-Teams are obviously choosing between Roy and Cliff Lee when considering adding pitching depth.
-There is also an obvious trade-off in what teams want in return: a half-season rental with less payroll/more prospects given, or a year and a half with more payroll/fewer prospects (depending on how much money the Astros are willing to eat)? If it's the former, Cliff Lee is your man. If it's the latter, you're obviously interested in Roy.
-The Mets, Nationals, Dodgers, Rangers, and Twins are all reportedly interested in both , with more teams seemingly interested in Cliff Lee, who's younger, cheaper, healthier, and has been to the playoffs (and dominated) more recently than Roy. But there are problems with all of the rumored teams and Roy's interest - despite him pleading to be traded anywhere (Long Island Ducks? For Rickey Henderson? I smell a payback deal...).
-But there's one hitch when it comes to the Rangers and Cliff Lee - would the Mariners trade Roy within their division? For a team that's 12.5 back of the AL West lead (held by the Rangers), you might think they wouldn't care. But note the Astros' reluctance to trade anybody to the Cardinals, and they're currently 11GB of the Cards/Reds for the NLC lead.
-I just don't see too many teams trading within the division in June, and if that's the case, then you can rule out the Rangers getting Cliff Lee. Especially if the Ryan-Greenberg group is approved for the sale (and it looks like they will be, likely by the trade deadline), they can get that infusion of cash needed to take on some of Roy's salary, should they go that route.
-Bottom line is this: the Rangers are real post-season contenders, still close to Mississippi, still in Texas, and Ryan apparently has a nice relationship with Roy. I think if Roy goes anywhere, he goes to the Rangers*.
*As with all other comments on rumors and trades, I have no source or fact to base this on. Just a logic-based opinion.