Her results during GE15 is a result of both lky effect and her hard work (of course with the help of pap grassroots networks) . The moment TPL speaks in parliament her weakness will start to show. She had not contribute anything worthwhile on the national stage which is why she merely add to the number in parliament. Instead focus on working hard on the ground and keep quiet.
For many voters it simply boils down to candidate Vs candidate and not party Vs party.
As the saying goes, "all politics is local' couldn't be more true here. Parliamentary performance is secondary . The candidate that can connect with the ground win. It same case with WP AJ GRC when they can improve on their showing despite TC controversy. Voters can see the hardwork they put in and the rapport build with their MP.
This is the incumbency effect. It surprising that gms didn't learn the importance of groundworks and thought he can do well by just parachuting into the ward with no ground support. He was fighting against pap foot soldiers and their grassroots system, not just tpl.
The result he gets is not surprising.