The Eagles paid Jon Runyan about the same amount about 4 years ago. It started a trend for some teams to pay quality RT's bigger salaries. Runyan has been a key compenent to the Eagles team that has been to 3 consecutive NFC Championship Games.
The Texans think they have acquired another Jon Runyan in Todd Wade. He may not have the same impact, but that is their belief.
I personally think that Wade is a superior pass and run blocker compared to Greg Randall. DD and Hollings should be able to run comfortable to the right with Wiegert, Wade, and either Joppru or Bruener blocking. It would be a bonus if Wand and Pitts developed cohesiveness on the left side too.
With the exception of Wand, the starting linemen seem more suited to run blocking than pass blocking. That shows you that the team has build this line to match their vision of run first, pass second.