The Astros optioned Teng to Triple-A Sugar Land on Sunday, Matt Kawahara of the Houston Chronicle reports.
Teng was activated from the injured list in mid-July after missing a few weeks due to a knee sprain, but Houston elected to demote him after just two appearances, during which he gave up two runs on three hits with a 4:2 K:BB and four hit batsmen across 4.1 innings. The right-hander pitched to a 2.19 ERA, 1.05 WHIP and 8.8 K/9 through his first 17 outings of the year, but he has a 6.89 ERA across his past eight appearances (31.1 innings).