#3 Serge Gnabry
Gnabry spent part of his youth career at Arsenal before joining the senior squad in 2012. In his four years under Wenger, Gnabry played only 10 times and netted once.
The youngster had to deal with multiple long-term injuries which prevented him from playing regularly. The winger was also being pushed down the pecking order when Alexis Sanchez arrived and the rise of Alex Iwobi who can play on the flanks.
After leaving the club, Gnabry had a great season with Werder Bremen, scoring 11 times in 27 games. His great performance attracted interest from Bayern Munich who signed him in 2017.
Joining Hoffenheim on loan this season, he has 6 assists and 10 goals in Bundesliga. At the tender age of 22, there is a bright future for him at Bayern and Arsenal should not have let go of this young rare talent.