The chance for Cheslea is about 50 percent according to the rates we can see but the chance for Aston Villa is 25 percent and this shows us that even if Cheslea doesn't win this game still Aston Villa can't have too much chance against this team.
Here are the updated rates for this match I think considering the weak performance of Chelsea and the unstable results they got, we can't try betting on a draw.

The difference in odds is quite significant and indeed, as the host, Chelsea is naturally the favorite. But just seeing the results that Chelsea got in the previous few matches made everyone sick and it was impossible for anyone to bet on their victory. Even last week against Bournemouth they only drew and I couldn't stop laughing at that result.
Well, however, the bet on Aston Villa winning is the most reasonable and I think Unai Emery's troops will win again by silencing Chelsea at Stamford Bridge after the last time they did it last April.
Seeing Chelsea's performance, they have not yet found their best form. And the consistency is not visible at all. This will definitely make everyone hesitate to bet on Chelsea. And yes there will definitely be many who don't want to bet on Chelsea. I personally would even prefer to skip betting on this match. Because we don't know whether Chelsea will rise in this match or whether they will get worse. I really can't predict Chelsea's performance this season.
And if I change my mind. Then maybe I would also prefer to bet on Aston Villa. Because historically these two teams have met, we can see that Aston Villa beat Chelsea last season. Even then the match was held at Stamford Bridge.