Big questions will be asked if Donyell Malen keeps progressing at his current rate.
Starring for Bayern Munich and Germany, Serge Gnabry's rise has been so predictable away from Arsenal that it hurts.
Having broken into Arsenal's team as a teenager, Arsenal sold him when he struggled with injuries and loans, giving up on him too soon. Now he is one of their bigger regrets.
There may be an even bigger one emerging, in the form of Donyell Malen (above).
Malen upstaged Gnabry during the international break, as Holland took on Germany.
Dutch talent Malen scored an important goal to give the Netherlands the lead in a 4-2 victory with the game previously poised at 2-2, after Gnabry had scored the opener.
Just for Malen to be featuring in Netherlands' starting XI is significant, and alarming where Arsenal are concerned.
The Gunners smartly snapped him up from Ajax when he was just 16 years-old.
Now 20, the young striker is fulfilling his potential, away from Arsenal.
Arsenal sold Malen in 2017 to PSV Eindhoven. It seemed premature at the time, and he is proving this to be the case.
Malen has five club goals already this season and is flourishing in a key role at PSV. Now he is starring in international qualifiers for his country too.
While he would not have got this opportunity at Arsenal, there are two ways the Gunners could have handled this differently.
Malen should have been kept on, with an extended deal, and then loaned out.
If he had still been under contract to Arsenal right now, his value would be soaring, at least meaning the Gunners could cash in for a big fee.
Even better, they could be bringing him back next season to challenge for the first team.
Malen's situation, along with Gnabry, is not the only Arsenal error in recent seasons.
Jeff-Reine Adelaide is now starring for Lyon, and Ismael Bennacer at AC Milan.
These are bright talents who have slipped through the gaps at Arsenal and left for next to nothing, who are now worth millions.
It is a terrible look for the club, from both a sporting and financial point of view.
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