I think the problem with Senna is that pre-season, everyone expected him to trounce Chandhok, for a number of reasons:
1) Pre-season, Chandhok was generally viewed as a pay driver who was there due to sponsorship and/or Bernie Ecclestone, whereas Senna was seen as having genuine talent (GP2 results, near Honda/Brawn drive);
2) Senna had comprehensively beaten Chandhok when the two were team-mates in GP2, in as equal machinery as you’re going to get;
3) The Senna name, meaning people’s expectations are going to be higher.
However, because both drivers have been performing on a similar level, Chandhok has earned people’s respect, which he didn’t necessarily have beforehand. People have been pleasantly surprised by Chandhok rather than being disappointed with Senna – which is probably fair, going on the car they have! – thus more attention on Chandhok.