The German's decision to leave the Emirates Stadium due to a lack of playing time could come back to bite the Gunners but could they have done more to keep him?

"I want to keep Serge Gnabry and extend his contract. I think he's here now for a long time." Two weeks after Arsene Wenger announced his intention to tie Arsenal’s German hotshot down to a new long-term contract it was confirmed that the 21-year-old had signed for Werder Bremen on a permanent deal.
It was a decision which Gnabry mulled over all summer. Enquiries for the versatile forward kept on arriving following an array of superb performances with Germany at the Olympics where he scored six goals to finish as top goalscorer.
Several major European clubs, including Bayern Munich, expressed a keen interest in signing Gnabry but were quickly told that he was not for sale - until the player eventually came to the conclusion with his father and agent Jean-Hermann that leaving Arsenal would benefit his career.

Gnabry joined Arsenal from Stuttgart in 2011 for a fee in the region of 100,000 euros. He flourished in the Gunners' academy system and revealed that the reason why he left Germany for England was because of Wenger’s philosophy in giving young players a chance.
“I knew that the manager [Wenger] banks on young players and I will get my chance here”. Unfortunately for Gnabry a mixture of injuries and players ahead of him in the pecking order curtailed his opportunities to show what he could do on the pitch.
“He is really uncomplicated in day-to-day life”, Gnabry said about Wenger. “He talks a lot to me, and points me in the right direction. But what the future has in store for me is entirely up to me and how I present myself in training and during the games.”
Perhaps the key is reading between the lines when you analyse why Gnabry didn’t make it at Arsenal. Was it a mixture of impatience and stubbornness or simply a burning desire to show everyone what he can do elsewhere?
Knee injuries can destroy players and the lingering doubts in Gnabry’s mind were made stronger when he agreed to join West Brom on loan last season. He made just one appearance under Tony Pulis, a manager who didn’t like Gnabry’s defensive workrate and reported reluctance to track back. Arsenal exercised an option to cut the loan deal short and Gnabry was left feeling dismayed at the way he was treated.
There were doubts from the Arsenal hierarchy as to whether Gnabry could recover from the knee injury he sustained against Bayern Munich in March 2014. It came at a time when he was playing regular first-team football and meant that he wouldn’t play at all in the following season. While Gnabry remained unsure whether he would be offered a new contract, Arsenal waited to see whether a full recovery was in sight. Coming into the 2016/17 season with less than a year left on his contract put Gnabry in an excellent bargaining position and allowed him to leave the club for a fee just under £5m, much to the frustration of many Arsenal supporters.
His performances at the Olympics, where he scored six goals in five games, made everyone stand up and take notice of the tricky, skilful winger once again. From the second-youngest player to ever score for Arsenal, to a silver medallist at the Olympic Games, Gnabry has taken the world by storm and told Wenger he didn't want to be back-up behind Theo Walcott, Alex Oxlade-Chamberlain and Alex Iwobi. It's a decision which seems to have paid off so far, with Gnabry scoring two goals and making one assist in five games for Werder Bremen this season. 
Talk over Gnabry's future will continue over the coming seasons if he maintains his excellent form. Reports suggest that he has a release clause in his contract which would see him play one season at Bremen before joining German champions Bayern. It would be a lucrative move if it happens and Wenger could be left to further rue not doing more to keep Gnabry when he was sitting on the sidelines because of injury.
Could he be the one who got away? We'll find out soon enough.