Willian joined on a free transfer from Chelsea, securing a big wage on a three-year deal, and seemed to immediate reward Mikel Arteta - who was instrumental in his signing - with two assists on his debut in September.
However, just one assist in 24 games followed and Arteta lost faith in Willian. The Brazilian nwo appears to have turned a corner with four assists in his last five appearances.
Speaking to ESPN Brazil, Willian said: “It really was a very difficult start, apart from that first game against Fulham, where I had a good performance [setting up two of the three goals in a 3-0 win], I managed to make a good game.
“Even after that game there were some games that we won, I even had a good game, but then we ended up getting a bad streak.
“I also got a bad streak and I think my worst professional time to date, since I went up at Corinthians and was sold to Ukraine, then I arrived at Chelsea, without a doubt. This phase that passed now was the worst time that I think I lived as a professional.
“Of course, when you live in a difficult moment, you get really upset and try to find solutions, a way to improve, try to help the team.
“That's what I've been doing all this time, I never stopped training, to work, to dedicate myself as much as possible.
“It took a little while to leave, but lately in the last games I've been playing well again, standing out with assists, playing well. So I'm happy to be back to find my good football.”
Willian believes Arsenal are in good hands under Arteta and have all the tools they need to reclaim their status as a powerhouse in Europe.
Spaniard Arteta led Arsenal to the FA Cup last season but the team have failed to kick on and are currently ninth in the Premier League, a competition they last won in 2004 under Arsene Wenger.
Arsenal's FA Cup defence was ended by Southampton in the fourth round and the Europa League is their only hope of silverware this season, but Willian is confident they are on the right track.
"I think it has the potential to be a great project, it's a great club, it's in the hands of a good manager, he has everything to become one of the best managers in the world," Willian told ESPN Brazil.
"Arsenal has everything to become a powerhouse again, to fight for titles, to play in the Champions League again, that's what we players want.
"Arteta is doing a great job, he is always looking for the players in the best possible way, giving them ideas, guiding them, showing them what he wants. Arsenal is in good hands."
Additional reporting by Reuters.