Sanchez was the #4 overall pick in the 2009 draft, selected by the Pittsburgh Pirates one pick after Donovan Tate was selected by the Padres, two picks after Dustin Ackley was selected by the Mariners, and one pick before Matt Hobgoob was selected by the Orioles. Other than Stephen Strasburg at #1 and Mike Trout in the latter part of the first round, the 2009 draft was pretty unimpressive, as you can probably divine from look at at that group that went numbers two through five.
Sanchez has 156 career plate appearances in the majors from 2013-17, though almost all of that came from 2013-14 with the Pirates -- he had just 9 big league plate appearances in 2015, 0 in 2016, and 1 last year with the Braves. The bench coach for Pittsburgh in 2013 and 2014, was, of course, Jeff Banister, and that connection may have something to do with the Rangers acquiring Sanchez.
Sanchez has bounced around quite a bit since being released by the Pirates in January, 2016 -- he signed with Toronto a month later, was released in July, 2016, signed with the Giants in early August, 2016, became a free agent at season’s end, signed with the Angels in November, 2016, and then was traded by LAAAAAAofAnaheim to the Braves on August 31, 2017, in exchange for Brandon Phillips.
This appears to be the Rangers continuing to sift through catching depth options, and Sanchez will join Cameron Rupp in sharing the catching role for Round Rock for the time being, I would assume.