If you can get a healthy RB that has been producing the past few weeks for Alexander, I do it in a hurry. Same thing goes for a QB/WR if you have a need in that area.
Fact is, Alexander was not running well even before he broke the foot. Blame it on the week 1 ankle sprain, or you can blame it on the weakened O-line, tough schedule, etc. There are no guarantees that even if Hasselbeck comes back 100%, Maurice Morris and Mack Strong go back to their 1 carry a game average, and SA comes back 100% fully healthy that he will be the same level of RB he has been for the past 5 years (forget record breaking TD Alexander was saw last season).
Face the facts people: Alexander has been valuable on name alone since the end of 2005. If you are a team who is watching your season go into the crapper waiting for your savior to come back next week, I wouldn't bank on it. If you can get a RB like Kevin Jones or Chestor Taylor for Alexander, I would do it in a heartbeat, and I would have done it 2 weeks ago. They can be equally productive, my guess is that they will be more productive, and they are playing and healthy right now.
Perhaps now that SA is expected to return shortly, his value is on the rise. Keep holding onto hope if you want to, just like the guy who hangs onto his "studs" going into week 5 with an 0-4 record.