Theo Walcott already carried the excess psychological baggage of playing for Arsenal and so the past six months could have been too much for him. Or, indeed, anybody. The new contract issue, which mercifully has now been resolved, was played out under a glaring spotlight and generated an inordinate number of headlines.

"At least it gives the newspapers something to write about," said a fed-up Arsène Wenger at one point, and it was easy to see where the Arsenal manager was coming from. Walcott scores highly on the football media's index of A-Z listers, a complex formula based on youth, talent, excitement value, geography of club, price tag and international caps. When he is central to a saga that is heavy on intrigue, it is going to be written about.

As Arsenal regrouped after their latest angst-inducing defeat – Sunday's 2-1 derby loss at Chelsea – Walcott represented a glimmer of light. It was possible to paint his second-half performance, complete with eye-catching goal, as an emergence from a long, dark tunnel, after his signing of the contract extension last Friday. Except that it was his 15th goal of the season and he has played consistently well, when selected, throughout. His numbers are the best of his career.

Walcott talked of the extent of the background noise, which has been loud and testing, as he delivered a heartfelt call for Arsenal's players to get a grip, to shoo away the demons that are suffocating their talent and expression. "There's a lack of belief as to how good we can be," he said. Wenger and the club need more of the sort of character that Walcott has shown this season.

"It has been tough through the negotiations," Walcott said. "It hasn't always shown on the pitch and off the pitch but deep down, it has been tough, not just for me but for my family, my partner. They were all getting hit with it every week and every day. I'm so pleased it's over.

"I can deal with the speculation but it's more my family and friends, who I thought might not have been able to cope. I've dealt with it and I think that shows that I've matured as a man. I can deal with these sort of things."

Arsenal's mental toughness or the lack thereof has been a burning issue for what has felt like an age. It is maddening for all concerned, especially Wenger, who has come to lament how the players' overwhelming desire to impress has sometimes crossed the line into anxiety. They were dismal in the first half at Stamford Bridge, when they trailed 2-0, and they were off the pace at home to Manchester City the previous weekend, when they fell behind by the same scoreline. Only when both games appeared to be out of reach and, perhaps, the pressure was lessened, did they begin to play, although they could not turn around either result.

There was a time when Wenger would talk of the youth of his team as a mitigating factor but a shift in his transfer policy since the summer of 2011, which has led to the pursuit of more seasoned internationals such as Mikel Arteta, Per Mertesacker, Lukas Podolski and Santi Cazorla, has diluted the excuse.

The stock reaction to an Arsenal defeat is the demand for further investment, which is fuelled by the knowledge that there is a sizeable kitty available to Wenger. The team's creative options looked thin on Sunday, when Wenger was reduced to summoning the forgotten man, Andrey Arshavin, even if the manager would point out that he was without a quintet of potential game-changers – Arteta, Podolski, Alex Oxlade-Chamberlain, Tomas Rosicky and Gervinho.

Wenger is scouring a difficult January market and there is no doubt that a new signing would be a tonic. But what is of overriding importance is that the current squad rouses itself. Arsenal play their game in hand on the top four at home to West Ham United on Wednesday night but even if they win, as they expect to do, they would still be four points off Tottenham Hotspur, the fourth-placed club.

The pressure is rarely less than extremely high at Emirates Stadium and the club have faced the prospect of failing to qualify for the Champions League before, only to rally when it mattered. The thought of falling short for the first time since 1997 is unthinkable on a footballing level and, at the same time, motivating.

"The Champions League means a lot," Walcott said. "It's one of the reasons why I decided to stay. I'm only 23 and yet I've played so much in the Champions League. I know how good it is and that our players will get better from playing in it. It turns you into a better player.

"I feel that we can and should be there, and I still think we will make it this season. This team is getting better every year and we don't want to be standing still. We need to be right up there at the end of the season. We blow hot and cold at home so we need to be positive and show the sort of commitment that we showed in the second half at Chelsea. Then, we should be fine."