With the 5-0 home win against Crystal Palace, Arsenal went back to winning ways following three winless matches in the Premier League. This win has kept Arsenal's title race alive, and they will not want to lose another match soon. Arsenal has overtaken Aston Villa to occupy the 3rd position in the Premier League.
Fulham did humiliate both Nottingham Forrest and West Ham by scoring 5 goals without conceded, yet they're struggle when they face top clubs. Crystal Palace is nothing different with them, a weak club, so I don't expect Arsenal will join the title race just by winning with big scores against weak club.
Although Arsenal has an advantage in terms of players availability than Liverpool...
Every match in the Premier League is a big game because you are not sure of taking the whole three points until you have played your match and won. Arsenal is already in the Premier League title race because they are in the third position in the Premier League table, with 43 points and two points behind the Premier League table leader.