Smith has been spectacular for us in the early season as a lone striker. He struck 2 fantastic goals against Arsenal and Norwich. (Sadly, how soon people seem to forget about those goals). He has shown great potential in him to succeed at Man Utd when he was given enough matches. He is very useful as a backup striker. He's certainly better than Chelsea's backup Charlton Cole. I would definitely not write him off yet. Moreover, given Saha's injury problems, it is very likely that we'll need a 4th striker. If any 2 of Saha, RVN or Rooney are injured or benched for whatever reason, we'll be forced to play 4-5-1 again.
Would he even get on Chelsea's bench? Smith is much better than both drogba and c. cole. First of all smith actually has talent and potential, second he plays for man. utd., of course he would be starting.