“Arsenal was a club on a downward slope for two years when I arrived,” the Spaniard told France Football.
“We stopped that slide and even started to straighten the club out with a Europa League final and fifth place in the league, only one place behind Tottenham, even though we only took one point in the last five games.
“We had Champions League qualification in our hands and it went wrong at the end. But it was a good season and we had the idea to continue this progress.
“But we lost our four captains: [Laurent] Koscielny, [Petr] Cech, [Aaron] Ramsey and [Nacho] Monreal.
“We were missing personalities for this season to stay on track, and some stars did not have the right attitude and asked for more than they gave.
“Considering all that, it would have taken more time to transition successfully into the new Arsenal that I wanted.”
The former Arsenal boss also felt that he could have done better had he stayed on at PSG.
“In Paris, I missed the chance to become the best coach in the world,” he told France Football. “I won the league, four domestic cups and two Trophees des Champions. But the ultimate goal was the Champions League.”
See More: Top 5 Arsenal Managers With Best Win Percentage