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.
In this option Chelsea is superior and only has low Odds because they have a home match but if you study it carefully a home match is not a guarantee that Chelsea will be able to give their best results later.
I think few people will dare to bet Chelsea as the winner in the match against Aston Villa and the best option is to take a draw or speculate that Aston Villa will win the match later.
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.
I also think the same as you who would rather speculate on Aston Villa winning than betting on Chelsea just because of the Odds advantage and the home game.
Look at Chelsea they are experiencing a worse slump than before and it looks like Pochettino will be a little confused if his team lose to Aston Villa in their home match and so far Chelsea have only managed to get 1 win.