This goes for most pieces but Arsenal fans, please work with me beyond the headline on this one.The news, broken by The Athletic on Saturday, that Arsenal and Besiktas had reached a €20million (£17.1m, $22.9m) agreement for Leandro Trossard to move to Istanbul was met with sadness, and that feeling may be necessary more often for the club to evolve.Personal terms are being finalised, but no move is expected to go ahead until he is back from the World Cup, where he is starring for Belgium.Arsenal’s record of selling players pales in comparison to that of their Premier League rivals.Last summer, only three teams had lower record sales than the £35m Arsenal received from Liverpool for Alex Oxlade-Chamberlain in 2017. There are many contributing factors behind the fees players are sold for but one that feels pertinent here is the demand for a particular player (as well as their perceived ceiling and wages).What has not helped Arsenal in the selling market is that since Oxlade-Chamberlain’s departure, many players who leave north London do so when they are either on a decline or have hit rock bottom.Emotions ran high when Mesut Ozil and Pierre-Emerick Aubameyang were paid to leave the club with contract terminations in 2021 and 2022 respectively, but there was an acceptance that their best years were behind them. Outside of these supremely talented players, most who leave Arsenal do so without the outpouring of emotion that surrounded the Trossard news this week.Trossard celebrates opening the scoring in Arsenal’s 4-1 win over Tottenham Hotspur last season (Justin Setterfield/Getty Images)Academy players are the exception. The respective sales of Alex Iwobi (£28m potentially rising to £34m to Everton in 2019), Joe Willock (£25m to Newcastle United in 2021), Folarin Balogun (£25m potentially rising to £34.4m to Monaco in 2023) and Emile Smith Rowe (£28m potentially rising to £34m to Fulham in 2024) were all contentious, despite the respectable fees generated.These players all left because they felt they had to for their careers to flourish. Trossard’s departure would represent something different as he is an exceptionally valuable player for Arsenal.