In terms of performance Chelsea are still at the bottom and that's true so Arsenal are worthy favorites in this match it's just that we can't completely doubt Chelsea and think they can't play because even though the beginning of this season they were not too erratic even seemed bad but in some matches they were able to bring 3 points in the last few matches on the other hand, Liverpool have also been held to a draw by Chelsea so I think even though currently Arsenal are above them but Chelsea can't be underestimated.
Underestimating Chelsea would be the greatest mistake Arsenal would do and I hope they don't, because we have seen teams in bad shape and at the bottom of the table strive to get a draw when they meet with big teams, they sometimes end up winning big teams. Moreover Chelsea is only been doing poorly recently but they are not a very bad team yet as they still have some good quality players.
Chelsea isn't yet so bad enough to write them off, recently the had two wins back to back and this could mean they are gradually getting better although they are still characterized with some inconsistency but they have quality players enough to get back bon their feet in time, their morales is still very high at this point coming from their most recent wins, so facing arsenal with such energy would be fruitful.
Arsenal is going to have it tough with Chelsea even if they eventually win they would have to work to deserve it. Before the game with Burnley it was speculated Chelsea would draw or probably loose but then it turned out a surprise to most of us at the end of the day, so most definitely Arsenal will not have it easy and if you must bet on them I advise you avoid predicting the winners rather predict number of goals, 1.5 and above goals.
Currently, with Arsenal's conditions, they are indeed capable and the odds are also quite good with 2.17, but that cannot be used as an excuse for them to underestimate Chelsea because it cannot be done.
They are favorites, their conditions are better than Chelsea but when they try to underestimate Chelsea then this is what makes Arsenal destroyed.