After all, the 28-year-old American had failed to impress during a five-year spell in Europe before returning stateside to join the Carolina RailHawks of the NASL in April 2014, where an uneventful stint left him contemplating retirement.
Fast-forward several months, though, and Grella’s doubters find themselves eating humble pie.
On Friday night, the New York-native put in another impressive left wing display, as he bagged his sixth MLS goal of the season to help his hometown club claim a 3-2 comeback win over the Chicago Fire.
| Vs Chicago
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The Fire had gone 2-0 up within the opening 26 minutes at Red Bull Arena through a Jeff Larentowicz penalty and David Accam strike, before Bradley Wright-Phillips started the home side’s comeback with a simple finish just before the half-hour.
10 minutes later, the Red Bulls found their equaliser thanks to Grella, as the skilful wide man connected with Lloyd Sam’s cross inside the six-yard box, before turning quickly and firing home to put both sides on even terms heading into the break.
Jesse Marsch’s men would have to wait until 20 minutes from the end to grab the winner, however, when Sacha Kljestan slotted in a spot-kick after Sam was brought down in the area to make it five victories from the past seven matches.
Now top of the Eastern Conference with 45 points from 26 games, the club are in the thick of the Supporters’ Shield race heading into the run-in and, after a tumultuous off-season, it cannot be overstated how much of an achievement that is.
Having lost both Thierry Henry and Tim Cahill in the winter, plenty predicted they would be floundering around the bottom of the table this term, while the controversial sacking of fan favourite head coach Mike Petke had also left fans in a state of uproar.
The mood around Red Bull Arena is somewhat different at this point, though, and that is thanks in no small part to the contributions of the like of Grella, who have stepped up to be replace the departed stars in seamless fashion.
The ex-Leeds misfit in particular has proved one of the surprise packages of the MLS campaign, establishing himself as the first-choice starter on the left wing – even after the summer signings of Shaun Wright-Phillips and Gonzalo Veron, while recording six goals and seven assists in 25 league games.
His resurgence in MLS comes after he has been criticised in the past for both his work ethic and failure to fulfill his potential but, speaking to the club's official website back in June, head coach Marsch was quick to paint a different picture of the versatile attacker.
"I spoke with Mike, maybe, a month ago," he said. "And there's been criticism about Mike, right? Publically, in the media, and I just said to him that first of all, within the team, he's established himself and the guys believe in him and having him on the field, everybody knows he's been a big piece for us.
"I think he took that the right way and ran with it and the confidence that he's had over the last month has grown and grown and grown. Even in the tough moment for the team with results, I think that Mike has been one of the guys that's been reliable and has gotten better."
Dubbed “Grelladinho” for his highlight-reel performances, there is now growing support for the former US Under-20 international to earn a first senior call-up and, while he missed out on the squad for the September friendlies against Peru and Brazil, Jurgen Klinsmann will not be able to ignore him for much longer if he keeps up his current form over the coming months.
That would certainly mark an amazing turning for the man who previously bounced around the English lower leagues and came close to quitting the game altogether, and the Red Bulls are now reaping the rewards from giving him a chance to get his career back on track.