Lisa Helps may not have gotten 50%+1 fo the vote but her margin over Stephen Hammond was large enough that in a two-person race she would still have won. to suggest that she only won because of a split vote is being willfully blind to reality. To blame a third candidate for the loss of a candidate is simply avoiding the truth that Hammond did not campaign well enough to win. This sort of thinking does not constructively improve the opposition to the mayor and make a win in 2022 likely against her successor.
Vote splitting is almost always a myth or an impact that is very small
Two factors come into play:
Every candidate causes some people to vote that would not have voted otherwise. Something like 5% to 30% not voting is a reasonable assumption in most elections
No candidate's votes will ever flow 100% to another candidate - anything over 80% is unrealistic, there is more than enough data out there to clearly show this.
So where does this leave us?
Let's do a very generous Hammond scenario using the best of all possible worlds -this is unrealistically optimistic for Hammond
The voters of candidates 5-10 (1,315 votes) I am assuming will drop to 1,200 votes evenly split Hammond and Helps
Bruce McGuigan - of his 2,377 I am assuming 2,200 would have voted and given his platform I give Helps the edge, 1,200 for 1,000 for Hammond
Mike Geoghegan - of his 4,335 votes, I am going to assume 4,200 would still have voted and I am going to give Hammond 3,360 and Helps 840
Based on this what we get is Helps at 15,282 and Hammond 13,677 she still wins by 1,605 votes 52.7% to 47.3%.