In absence of Neymar Jr their attack still produce good chances for the Al Hilal and have three goals which bring them to the top of the league table now with this performance and aggressive approach most chances they will be stayed at the top of the league table for long time because right now no other team is having solid performance like them for having good result.
Al Hilal is a most successful club in Saudi Arabia and Saudi Professional League and they achieved it through their long history with many previous years without Neymar.
The Brazilian player can help Al Hilal to become stronger in attacking with his creativeness and his amazing attacking skills but Al Hilal can play well and win Saudi Professional League without Neymar. Like Al Ittihad won the league last season without Messi and they won it over Al Nassr with Cristiano Ronaldo. Neymar is important for Al Hilal but he is not all they have and their strength won't become zero without Neymar.
Neymar Jnr's constant injury crises is something that he doesn't cause for himself and that's why I don't think he should be blamed for the injuries that he always sustains. Though Neymar is a player that in many occasions has been involved in off the field drama, he still delivers good football whenever he's been called to play. I think he needs to stop getting himself involved in any drama at the moment and focus on his football career.
I believe Al Hilal did knew about Neymar injury record as fans we already knew about it. As a club with many staffs and teams, they did have detailed research and considered a lot before spending big cost for PSG to bring Neymar to their club and Saudi Professional League. I also believe they did accept that Neymar can have some injuries during his two years contract with Al Hilal.
With lucrative salary received from Al Hilal, Neymar will enjoy his life more and he will get more injuries, first because he will be older and second because of his less professional lifestyle and training in Saudi Arabia.