There's one question that continues to nag at Greg Vanney: Can his Toronto FC team be the best MLS side ever?

Over the past two-and-a-half seasons, Vanney has guided TFC to their first-ever playoff appearance (in 2015) and to an MLS Cup final (in 2016). This season, he's managed a roster beset by injuries and international absences and guided it to first place in the Eastern Conference and a league-best 40 points through 21 matches.

Vanney's question, though, isn't presumptuous. He means no disrespect to the other MLS contenders. No, Vanney looks at his team's roster and he sees a potential for greatness, greatness that he hopes to unlock.

What he's accomplished so far at Toronto, especially after taking over the team late in the 2014 season, has been nothing short of a miracle for the historically moribund franchise. Before Vanney, TFC had been a meat grinder for head coaches, chewing up and spitting out eight of them in each of the franchise's first eight seasons.

But in a few short years, Vanney, whose TFC side will host New York City FC on Sunday afternoon (2 pm ET | ESPN, ESPN Deportes in the US; TSN 4/5 in Canada) has evolved into one of the most talented tacticians and man-managers in Major League Soccer.

“When you talk American coaches, a lot of times people will talk Peter Vermes or Tab Ramos or Jason Kreis,” said Vanney's former coach and new LA Galaxy boss Sigi Schmid. “I think Greg needs to be in that same discussion.”

While it might seem like Vanney's transformation into one of MLS' best coaches has happened overnight, his success has been decades in the making.

Vanney was part of a generation of American soccer players whose education in the sport was their own responsibility. There was almost no soccer on television and youth soccer could hardly be described as competitive. Vanney's club teams seldom practiced more than twice a week and then only part of the year.

So all-consuming was the young Vanney's passion for the sport that when he wasn't training with his club team or imitating Ronald Koeman's precision passes in the backyard, he was in front of the television analyzing VHS recordings of his team's matches. By age 12, the precocious Vanney was already coaching kids at the local YMCA.

“I think his truest passion is coaching and being on the field,” says Toronto FC general manager Tim Bezbatchenko. “He has a love of coaching and I think that with his integrity and work ethic and his passion... [it's] a winning formula.”

From a coaching perspective, you would think that Vanney was the spiritual successor to Star Trek's Spock. His colleagues at TFC describe him as calm, cerebral, logical, curious, inward-looking and he approaches his job like an engineer. In his words, “Find the problem and then find the solution.”

There are signs, however, that Vanney's personality and approach are beginning to change, if only slightly. Against NYCFC last week, Vanney received a red card for the first time in his coaching career after he criticized the performance of referee Jorge Gonzalez. According to Vanney, there was nothing calculated about the outburst. The reaction was genuine and one that, according to his TFC colleagues, speaks to his evolution as a head coach.

Still, Vanney's own response to the outburst is telling.

“There's a time and a place for emotion,” he explains, “but even when I talk to the players on an individual basis I try to deal with them as human beings and as people in a non-emotional, here-are-the-facts and here's-how-I-see-things kind of a way and I think the players appreciate that.”

He never permits himself to get too high or too low. Win, lose, or draw, he's back to work the next day, thinking about TFC's next opponent. He earns the respect of his players because they see that he's as demanding of himself as he is of them. According to Schmid, Vanney's been that way since Schmid began coaching him at UCLA in 1993.

"You could tell he was confident in his abilities, but he was also the kind of guy who demanded a lot from himself so he demanded a lot from me as his coach and he demanded [it] from his teammates as well," Schmid says.

“The status quo is never good enough [for Vanney],” added TFC assistant coach Robin Fraser. “He wants to be better. He wants to be where the game is at the moment and he wants to be ahead of it.”

At every step of his career, Vanney's shown a constant and relentless drive to be the best. It's why he transferred from Florida International University to UCLA, despite no guarantee that he would earn a starting spot in Schmid's team. It's why he left MLS to pursue a professional career with SC Bastia in France, despite the challenges he knew he'd face as an American playing in Europe.

So when Vanney ponders that question – “Can we be the best team ever?” – he sees a problem in need of a solution.

“What does that [question] mean and how can we approach that every single day to make ourselves better?” he asks. “That's what we strive for.”

If his past is any guide, Vanney won't be satisfied even if he cracks it; he'll just move on to the next problem.