#3 Joe Perez
Perez isn't a name I would count on being traded as he is a member of the Astros 40-man roster, but it can't be entirely ruled out. Names like Joey Loperfido, Zach Dezenzo, and Will Wagner may not be on the 40-man roster yet, but stand far more likely to contibrute at the big-league level than Perez.
Perez came up briefly last season and picked up one at-bat in The Show. He is hitting .267 with a .744 OPS in 52 games at Sugar Land this season. He's blocked by Alex Bregman in Houston, and with so many teams hesitant to sell with seemingly every Central Division team in each league still in the playoff race, infielders ready to play aren't going to be readily available.
MLB.com recently ran Wil Myers as a potential trade candidate. Myers has been worth -0.8 bWAR and is hitting .189 with a 44 OPS+. If that's the top option, solid infielders are at a premium. Again, I wouldn't bank on seeing Perez moved at the deadline, but for the right rental, he could go elsewhere.