If the Texans’ need for a highly drafted outside linebacker picking up the slack for an injured starter sounds familiar, well, that’s because it is.

First-rounder Whitney Mercilus has the task of replacing SLB Brooks Reed, who filled in for former Texan Mario Williams in 2011 when Williams was lost for the season with a torn pectoral muscle in Week Five.

Fortunately, for the Texans, Reed went down much later, suffering a groin injury in Week 12, and the hope is that he will return to contribute at some point this season — or in the postseason.

Like Reed a year ago, when he outplayed Williams in the preseason and had fans wondering how defensive coordinator Wade Phillips would find ways to get him on the field, Mercilus came on like gangbusters in his first preseason action, leading Houston in sacks and outplaying Reed and fellow outside ‘backer Connor Barwin. In fact, Mercilus has more sacks than both Reed and Barwin this season — despite not starting a game yet — and stands a strong chance of finishing second on the club in sacks.

The plan is for Mercilus to take Barwin’s position on the weak side on run downs, with Barwin moving across the field to the strong side, where he will have greater coverage responsibilities. Look for Barwin to move back to the right side of the defense on passing downs, though as one source wondered aloud, “perhaps it makes even more sense to keep Mercilus on the weak side, given he’s gotten home with the most consistency?”

Could a strong showing down the stretch make Barwin, a free agent after the season who has not matched his ’11 production, expendable, much like Williams was a season ago given Reed’s fast ascension? The possibility shouldn’t be ruled out, we hear.