According to Matt Barrows of the Sacramento Bee, the 49ers are looking to bolster their outside linebacker depth by signing 35-year-old Clark Haggans.

A 12-year veteran, Haggans started 16 games for the Arizona Cardinals last season, grading out as the team’s best linebacker. Haggans’ three sacks, five quarterback hits, and 15 hurries, though not staggering numbers, were unmatched by any other Cardinal defender. In limited opportunities, Haggans successfully stopped 52% of passes thrown his direction and 63% of runs toward his zone.

For comparison, the 49ers only back-up last season, Parys Haralson, accumulated two sacks, five quarterback hits, and 10.5 hurries, while successfully stopping 83% of runs plays and only 39% of passes. In all, if Haggans continues to play at his 2011 level, he could usurp Haralson’s role as primary back-up to Aldon Smith and Ahmad Brooks.

Haggans could be subject to league discipline after spending 48 hours in a Pennsylvania jail last April for driving under the influence.

No word on a corresponding roster move yet.