A write in will never win and I think we can send a stronger message by not voting for anyone in a particular race.
I'm assuming you're referring to the mayor's race? If someone receives a significant number of write in votes, you're effectively giving Carlo two years to discredit him. Why give him that kind of opportunity?
A write-in is hard enough to orchestrate if there is a candidate involved with it. Trying to "draft" someone for an office via a write-in I believe would be almost impossible.
I also believe that it sends a stronger message by choosing to submit a blank choice for any office where there is only one choice and you don't believe in that candidate. It's a vote of no confidence. To make it really effective though, you must convince people to exercise their vote in this fashion rather than choosing not to vote due to the lack of choices.