Agreed, but Sheed has always been essential in this series, regardless of how Garnett plays. LA has a bigger front line overall and Bynum is playing well. Glen Davis has had a few good plays here and there, like the charge he took on Kobe, but he doesn't match up well with either Bynum (too big) or Gasol (too good).
I might add that S. Williams will probably not play for the rest of this series due to his awful 4 minutes, so that puts pressure on Sheed to perform. Also why not activate Scal over Quis?