There are decisions, then, for Fulham and Parker on whether to stick with the approach that got them promoted.
"The big lesson today is to understand the fine margins in this division mean you can get punished," he told BBC Match of the Day.
"When you are a team like us that has come from the Championship you can't let defeat after defeat really cripple you. We are going to lose more than we win but as a team you have to keep learning and developing.
"It has been a quick turnaround for us. We have brought players in that will improve us and hopefully there will be more. We need to get them up to speed quickly."
Arteta admitted he was surprised at how well Gabriel played on his first game since March when Ligue 1 was curtailed.
"He hadn't played any football for six months so to come and play a game in the Premier League after training with the team for three or four days is a big task," he told BBC Sport.
"The boy showed a lot of character and what he can do. He can still improve a lot but he had a really good game.
"Willian knows the league, the country and is very settled here so I knew his performance would settle straight away."