In new left tackle Laremy Tunsil, the Texans see a dynamic blocker capable of protecting star quarterback Deshaun Watson.
Watson was sacked an NFL-high 62 times last season.
In three seasons, Tunsil has yet to be voted to a Pro Bowl, but the former first-round draft pick is regarded as one of the top young left tackles in the NFL.
Tunsil allowed only two sacks last season. He was flagged for nine penalties and 21 over the past two seasons.
"I feel really good about being able to get a proven left tackle to protect Deshaun Watson," O'Brien said.