David Beckham brought the attention. Thierry Henry injected further credibility.

But as far as Designated Players go, nobody in Major League Soccer history gave his team more for its investment than Robbie Keane, the 36-year-old Irish striker who will be leaving the LA Galaxy after 5½ seasons.

Clint Dempsey, Michael Bradley and Jozy Altidore shifted the paradigm and demonstrated that the domestic league could land the best domestic talent. Sebastian Giovinco and Giovani Dos Santos arrived in their primes and broke through another barrier for the league, arriving as in-their-prime stars. Kaka, Didier Drogba, Frank Lampard, David Villa, Steven Gerrard and Andrea Pirlo confirmed that there really wasn’t a name too big to be lured stateside at the tail end of his career.

But Keane, between the first and the last whistle, was the best on the field.

Like Juan Pablo Angel, Marco Di Vaio and Obafemi Martins, he needed no adjustment period at all to score a boatload of goals. And like Fredy Montero and Tim Cahill, he did so while instantly making his team better.

Yet Keane surpassed them all.

Because Keane was the lynchpin of a Galaxy dynasty that won three MLS Cups and a Supporters’ Shield in four years, connecting the dots between Beckham and Landon Donovan, and instantly setting the league aflame with his unfailing toil, deceptive quickness, merciless finishing and shrewd but underappreciated runs.

With 83 regular season goals in five seasons and change – of those, half of 2016 was ruined by injury – and nine more in the playoffs, his goals haul was enormous. But most of all, he added a venom to a team that had previously been a haphazard band of stars, imbuing it with toughness and tenacity.

“From day one, Keane has given everything to this team both on and off the field and has led our club to some of its greatest accomplishments,” said Galaxy head coach and architect Bruce Arena in a statement. “His resume and accomplishments speak for themselves; he has been the most successful international signing in this league’s history.”

In the regular season alone, Keane also doled out 45 assists, 18 of them game-winners while 26 of his goals won matches. He got 21 multi-goal games and four hat tricks. He was the league MVP in 2014 and the Galaxy’s Player of the Year four times in a row from 2012 through 2015. He was the fastest player in MLS history to reach 100 goals in all competitions.

Keane’s career took an odd path. He came up with Wolverhampton Wanderers, who had spotted him in Dublin and brought him over to England as a 15-year-old. After just two years in the first team, he was sold to Coventry City as the most expensive teenager in the history of English soccer. The Sky Blues flipped him to mighty Inter Milan after just a year. That’s where his meteoric ascent plateaued, though, as he never scored a league goal for the Italians.

For years, there was a sense about Keane that he’d never quite delivered on his enormous potential, as he joined Leeds United and then Tottenham Hotspur. But he became a productive Premier League striker, nabbing 80 Premier League goals in six seasons for Spurs before he bounced around some.

In all that time, however, Keane won nothing bigger than a solitary League Cup. He joined the Galaxy shortly after his 31st birthday in 2011, becoming one of the first European stars to arrive in MLS while still at his best. And then he went on the most productive run on his career. His goal tallies in his first four full seasons of 16, 16, 19 and 20 all either matched or exceeded his career high in 14 campaigns up to that point.

After shuttling between roles for his entire career, he became and remained an out-and-out striker and proved more consistent than ever. While MLS isn’t the Premier League, exactly, there was a sense that Keane had finally come into his own in Southern California. And in the process, he became the most successful on-field DP signing in the league’s history.

Keane doesn’t appear to be retiring just yet. “I believe that now is the right time for a new challenge as I look towards the next chapter of my playing career,” he said.

Perhaps the highlight of his MLS career was when a Reuters photographer snapped a picture of Keane with Beckham, comedian Russell Brand and some fans and identified him as just another fan in the caption. He was never the biggest star in MLS, but he had the biggest impact on the field.

Leander Schaerlaeckens is a soccer columnist for Yahoo Sports. Follow him on Twitter @LeanderAlphabet.