So if Ken Rosenthal is right, the Rangers were willing to do a Justin Grimm and Cody Buckel offer (plus something else, maybe Chad Bell, maybe Leury Garcia), while the Brewers were prioritizing getting a major-league-ready shortstop in the deal, and wanted Martin Perez if they couldn't get that shortstop.
It isn't surprising that Doug Melvin is looking for major-league-ready parts...his history, both with Texas and with Milwaukee, has been that, when trading veterans, he puts a premium on proximity to the majors, and with the Brewers having a lot of money committed to Ryan Braun, I imagine they're wanting to keep competitive now rather than truly rebuild.
If Rosenthal's report is true, it suggests that the Rangers were looking to part with a package similar to what they gave San Diego for Mike Adams last year...I've kind of thought of Cody Buckel as being this year's Robbie Erlin, the young, advanced pitcher who has climbed quickly up the organizational ladder and in the prospect rankings because of command and knowing how to pitch rather than because of raw "stuff," while Grimm is probably comparable to where Joe Wieland was last season. I suspect that Buckel is someone the Rangers are probably shopping, like they did with Erlin last season, not because they don't like him, but because they feel they would be selling high on him.
I'm also curious about whether the Rangers would have parted with Martin Perez to land Cole Hamels, a guy they reportedly liked more than Greinke. I don't think Perez or Mike Olt are "untouchable," but I do think the Rangers are only going to trade them in the right deal, and a two months plus playoffs rental probably doesn't qualify as the "right deal."