On the rare occasion when his name came up in conversation, it was usually followed by a, "Oh yeah, that's right. He is on the team!" kind of response.
The days of living an inconspicuous life for Wanamaker on the Celtics roster is a thing of the past now.
His journey to the NBA and current status in many ways speaks to how he has come to symbolize the resilient, tough-minded brand of basketball that is slowly but surely coming to define Boston's second unit.
Wanamaker, 30, is averaging 7.6 points per game off the bench, connecting on 50.5 percent of his shots from the field and 41.7 percent of his 3-point attempts.
He is one of four Celtics players to see action in all 19 games this season, but is the only one of the foursome (Jayson Tatum, Marcus Smart and Semi Ojeleye are the others) to see action in all of them as a backup.
And while there have been legitimate questions about just how impactful Boston's backups can be, they have shown lately a knack for making their presence felt at both ends of the floor.
In the past five games, Boston's bench has averaged 30 points per game which ranks fifth in the league during that span.
And their defense?
According to Hoopsstats.com, Boston has allowed second units to score a league-low 26.8 points per game in the past five games.
And the play of Wanamaker, at both ends of the floor, has been a big part of that second-unit success.
How he has thrived this season is surprising when you consider how things went last season and some of the Celtics' offseason changes.
Rookie Carsen Edwards had a red-hot summer and preseason, but has cooled considerably once the regular season began. And while the departure of Kyrie Irving (Brooklyn) and Terry Rozier (Charlotte) was supposed to create more opportunities for Wanamaker, that was far from a given when you consider the player Boston added to replace those two, Kemba Walker, is a three-time All-Star who rarely misses games to injury.
It didn't matter to Wanamaker, who returned to the Celtics convinced that he could play his way into a significantly more meaningful role this season.
In 19 games, he has played a total of 330 minutes.
Last season, he played a total of 343 minutes.
"It's been great," a grinning Wanamaker told NBC Sports Boston. "Just be out there with the guys, having an impact on the game, consistent games, consistent nights. It's been great for me. I'm happy with the role, cherishing every minute."
And as important as it has been to establish himself, Wanamaker also sees tremendous value in lifting up those around him who may be experiencing something similar to what he went through last season when he played sparingly.
"Brad has been great, checking in on me, seeing if I need anything," Edwards told NBC Sports Boston. "It's good to have teammates like that, for sure."
Last season was a tough-love lesson in humility and patience for Wanamaker, who came to Boston after spending the previous eight years playing overseas where he established himself as one of the top guards in Euroleague play.
But those accolades and praise did not translate to playing time initially, which Wanamaker admits is a tough pill to swallow if you've never experienced anything like before.
"Me going through last year, I am constantly talking to the young guys," Wanamaker said. "I'm constantly in their ears behind the scenes, because I tell them, the mental ... your mental [approach] can be really f'd up if you're not playing like you want to play or you come into a situation and look for it to go a certain way and it doesn't. I'm constantly checking in on those guys."
He gets it.
As much as he wants his own individual success and play to shine, he knows that the ultimate reward for him and the group is to find success collectively.
Still, this group, even at full strength, doesn't have the kind of second-unit sex appeal you find with a lot of reserve groups.
They are a blue-collar, often overlooked cast who collectively play with a toughness and resiliency that is starting to look more and more like their identity. It's one that the team's "old head" - Wanamaker - can relate to.
Don't miss NBC Sports Boston's coverage of Celtics-Heat, which tips off Wednesday at 7 p.m. with Celtics Pregame Live, and then Tommy & Mike have the call at 7:30 p.m. You can also stream the game on the MyTeams App.