It Depends (well, doesn't it always?)...
Cards either have lost (or are about to lose) Elton Brown (who despite being primarily a guard, was also listed as the #1 backup tackle on our depth chart).
This means that - if Gandy or Levi B were to go down next season, they'd be replaced either by Vallejo or Keith.
This may be better than OK if Russ G feels one or both is ready. But they're still unknowns at this point.
Most likely, Pace will want to be paid starters' money (and probably expect to start). He'd probably prove too rich for the Cardinals' blood. But if he were to accept the role of backup and mentor, he'd add a bit more stability to our O-line and would be a great pickup.
If.