To some extent stars might pull in the audience, and I guess that has been something pretty true for the past 5+ decades.
But there is a slight trend that has been seeming to grow during the last handfull or two of years... where it seems like the starpower of those actors names might not actually pull in people as much as Hollywood think it does, not anymore anyway. Exactly how big this trend is at the moment is hard to say, obviously, but it does seem like people are getting less and less impressed by who the actors are in the movies.
I think the easiest place to find the evidence of this is in the current superhero film genre (you can see it elsewhere as well with certain other actors who have not been in superhero movies), where many of the actors in them become really well known, almost universaly loved by the audience, etc. So naturally Hollywood will think "Oh man... these actors are getting a huge buzz right now! Put them in THESE movies as well and we will get filthry ritch!"... so they cast these actors in what ever other movies they have... and the audience goes... "...meh..." and do not watch those films. So Hollywood scratch their head a little in confusion as to what happend... those actors come back to their superhero movies, and suddenly the buzz is there again with those actors... so Hollywood thinks... "Well... it did not work that first time, but maybe this time it will! What could possibly go wrong?" and they cast those actors again in their next set of movies which are not superhero movies... and once again those movies barelly make it, if not bombs horribly, and Hollywood once again scratch their head in bewilderment about what is going on.
What Hollywood is having trouble figuring out as a whole, it seems, is that yes star actors can draw people... to a degree... but the absolut biggest draw for people is the movies them selves. Yes, Robert Downey Jr is probably the right guy to play Tony Stark, Hugh Jackman as Wolverine (even if many people where sceptical about him when he was announced back in the day), Ryan Reynolds as Deadpool, etc... they definetly helped the whole super hero movie franchise to find it's footing. But go back and pick almost any other good actor to play those roles instead of RDJ or HJ or RR, and you would probably have felt almost exactly the same about those actors and their portrayal of those characters as we have for the ones who have played those roles today.
It's hard to think that anyone else could play those characters now after we have seen them being played by those actors... but the truth is probably that as long as you cast talent for roles, it does not compleatly matter that much who it is, they just have to be capable of playing the character they are cast for. And in the end the movie it's self is what will, or will not, pull people in to watch it.
Make a good movie, put good actors in it... and you will probably be rewarded for your efforts. Since things will usually sort them selves out in the end. Because in this day and age of social media the word will usually get out quick enough, and if that word is "it sucks"... then you will end up with one of the world largest drop offs between week 1 and 2 in the history of box office... 81% - Batman vs Superman.
I still liked BvS sort of, but mostly because the things that I liked in the movie was really good and managed to outweigh the bad parts of the movie... for me atleast. But that is partly due to that I am a very forgiving person with things, and the range of quality I can find acceptable is much larger then most peoples, especially within the genres and styles of things which I like.