Consider the players that have come to excel over their time under Arena. Mike Magee is the most obvious choice at the moment. A player who failed to make a mark on the international level and who never quite lived up to his potential with the Red Bulls. While in New York from 2003-2008 Magee scored 23 goals in 130 appearances.
Bruce Arena brought him in for the 2009 season and since then he has scored 8 goals in 66 appearances. Add to that his fantastic habit of scoring goals in clutch moments and the playoffs. He's certainly benefited from the great service of his teammates, but as forwards around the league will tell you, sometimes it's the simplest goals that are hardest to finish. You could also point towards his display as a goalkeeper mid-season and while that was a great day for him, it's not really the point. Under Arena, Magee has found a consistency that other forwards around the league aspire to. For Magee to accomplish this while on a star studded roster is worthy of merit.
Arena picked up two more forwards this year who have struggled with other teams. Adam Cristman and Chad Barrett have both played some of there best soccer in a long time under the Galaxy coach. Chad Barrett has often been touted as a great forward who underperforms. While at the Galaxy he's scored 7 goals, the same as his season with Toronto the year before. However with Toronto, he was expected to be the fulcrum of the attack. While playing a less prominent role in the Galaxy attack alongside DPs, he's performed well. So much so that his ankle dislocation in practice to rule him out of the final is considered a blow against the team.
Cristman was a promising prospect in New England when he began his professional career. So much so that he resembled a potential replacement for Taylor Twellman. Injuries, poor form and a bit of a journeyman syndrome have seen Cristman float around the league until landing with the Galaxy. While his stats do not quite tell the tale of Adam's progression, observers have seen his game develop under Arena.
Even Clint Mathis had a solid final year under Arena. Apart from the forwards, Bruce Arena has done a fantastic job in developing players. Omar Gonzalez, Sean Franklin and AJ DeLaGarza continue to get better while under Arena. Perhaps what Bruce has going for him above all else is that he surrounds himself with veteran leadership. Gregg Berhalter, Frankie Hejduk and Jovan Kirovski are experienced veterans who have done wonders to mold the players around them. Add to that the Designated Player corps of Landon Donovan, David Beckham and Robbie Keane and Arena's recipe for success is clear.
It takes a powerful coach to develop youngsters, maintain high paid egos in the locker room and still navigate your team through multiple competitions and a league final. Supporters Shield(s), CONCACAF Champion's League and leading his team to MLS Cup Final(s) are all examples of Bruce Arena's influence on the Galaxy. Easy to see that he is still the best American coach to date.