Actually arsenal have a lot of money this season to spend, arsenal owner stan kroenke has allocated 215 million pounds for player purchases and so far they have got two big names namely Fabio Viera and Gabriel Jesus, Gabriel Jesus is rumored to be introduced to the public soon and reportedly Jesus will wear number 9 in arsenal, if indeed Youri Tielmans is successfully obtained by arsenal of course this will be good news for arsenal fans but hasn't the stock of arsenal midfielders currently piled up enough after Viera arrival?
In my opinion, rather than chasing players who play as midfielders, it is better for Arsenal to look for players who play as defenders to back up their defense next season and Martinez is a player that Arsenal should focus to get.
You could be right about that as they have quite a lot of midfielders in the team at the moment. But on the other hand while Tielemans is a central midfielder Vieira is more of a attacking midfielder. When we consider that Arsenal prefer the 4-2-3-1 formation most of the time, they can still find a place for both of them. There will be a huge competition among this many midfielders in the team though but I don't think Tielemans would have any problems on securing his place in the starting eleven.