I do not think that winning the title or not wouldn't be depending on Aubameyang and I doubt that he would be a decisive factor for how they will do this year. I am not saying he is an unimportant player or anything like that, he is good, but he is not team changing level of good anymore for sure, if he was then why would Barcelona even look for another player.
In the end, they got Lewandowski, who is actually a great player, and Chelsea had to wait for the last day, because they couldn't find anyone better and they were stuck with Aubameyang if you ask me. Of course he would be decent enough that he will be a striker that they needed, but won't be too much of a deal.
It's true don't overestimate Aubameyang, I also doubt Aubameyang will be an important factor for Chelsea to win the EPL trophy. Aubameyang
can make Chelsea much more productive, but if with the arrival of Aubameyang Chelsea can become champions I doubt that. Because
in my opinion, although Aubameyang is a good striker, he is not the type of player who can make a big difference to the team's performance.
Moreover, with your explanation which I think is quite reasonable, Chelsea signed Aubameyang because it was a last resort after Chelsea's
main target failed to be obtained.
Even according to rumors Chelsea tried to bring in Rafael Leao at the end of the transfer market by providing an offer of 80 million euros,
unfortunately AC Milan refused Chelsea's offer and did not want to let Leao who was a key player at AC Milan. After the failure to bring in Leao,
Chelsea did not have another choice of striker but to bring in Aubameyang. Moreover, Chelsea also refused to pay too much to buy Aubameyang,
therefore Chelsea used a trade-in scheme to get Aubameyang. This means that Chelsea did not prioritize Aubameyang from the start,
because maybe Chelsea themselves are a little doubtful that Aubameyang will make a big contribution to Chelsea.
I obviously do not think that Aubameyang is not going to be a very useful player for Chelsea in the long run. But at the same time, I also think that Chelsea will find a way to make him useful in some way.
There is no doubt that Chelsea will not become the best team in the league if they sign this player. However, I do think that he will provide some good stability for the team in my opinion.
It is true that Chelsea did have some difficulty scoring enough goals to win the game. As far as I am concerned, that problem will not be going to give panic anymore.
It is unlikely that he will be a game-changing player for Chelsea in the near future. But other than that he will be there to give Chelsea a more stable performance in the attacking lineup.