Arteta is one of the finest coaches in the EPL but as a result of him not winning a major trophy like the premiership or champions league yet after having spent such number of years in Arsenal with the quality of players in hia disposal he gets so badly underrated among other top coaches in Europe. So true, Arteta did made a horrible decision not signing a proper 9 last season in the January transfer and that was a price he paid both in the EPL and UCL, that's he has to sign Gyokeres now.
The main criteria to rate a coach include winning trophies, leading a club out of a lower division and in some cases, the revenue he generates for the club. Mikel Arteta is not growing young players that will bring huge financial returns like Arsene Wenger and Diego Simeone of Atletico Madrid. The club had kept investing in players only for the team to end up in the second position for several seasons. Yeah, he is a good coach, but he has not entered the books of successful coaches in Europe.