Arsenal boss Arsene Wenger paid tribute to Thomas Vermaelen after their Community Shield win over Manchester City.
Vermaelen formally signed for Barcelona yesterday.
"I allowed Thomas Vermaelen to leave before the end of the season because he was not playing regularly, he behaved outstandingly the whole season with dignity," said Wenger.
"It's difficult to maintain that kind of player at the top level if he doesn't play regularly. I'm quite grateful and wish him very well because his behaviour was outstanding even if he didn't play."
