According to the very reliable Jon Heyman and reported on MLBTR.

Further ...

he former Astros skipper has been the Braves’ third base coach this season and held that role for the Marlins over 2007 to 2009. Porter also has spent time with the Nationals and Diamondbacks in recent years. While he never meshed in Houston, Porter had been one of the more highly-regarded, younger coaches in the game prior to taking that gig and is still just 43 years of age.