That assumes Arsenal will win whenever Liverpool loses. I think last season or the season before that shows that Arsenal struggle to close the gap when it matters. They need to win every game to make sure they can win the title. Being complacent and believing that your competitor will slip up because you did is not really good. That being said, I think this applies to every team, not necessarily Arsenal only.
Yes, of course, all teams have improved their respective team conditions with a level of confidence in their efforts to win the title. With the support of new players, of course Arsenal will be even better with adequate quality in all lines. Because in reality, the initial foundation is much better when facing the next match, of course, that is what is being implemented at Arsenal now.