The former Manchester United, Real Madrid and England star has been the biggest name in North American soccer during his tenure and Arena has acknowledged just how much he has done for the sport in the region.
"It's great in that it brings closure to David's tenure with the Galaxy and MLS," Arena said.
"He's worth a lot more to the league than we ever could have thought.
"He's done wonders for the Galaxy and he's done incredible amounts of positive things for MLS. We are now a well-known league around the world and we can attribute a lot of that to David.
"His six years in MLS have been tremendous and I think it's more than any of us could have imagined."