But appearances can be deceptive - Bradley has shined at this World Cup, proving himself to be a classy passer of the ball, a smart organiser and a player whose German club Borussia Moenchengladbach could find themselves in a battle to keep hold of if he continues in this vein of form.
The son of U.S national team coach Bob, by the age of 22 he has already experienced Major League Soccer, the Dutch first division and the Bundesliga - picking up Dutch and German language skills and football skills along the way.
More pertinently, as he showed with his perfectly timed run and fine finish for his team's equaliser in the 2-2 draw with Slovenia, Bradley, who scored 18 goals in one Dutch season, also has a keen eye for goal.
His goal against Slovenia was moment he celebrated with a raging roar of delight, having completed a comeback from two goals down, but he refuses to see the moment in personal terms.
"It was something special to be part of. We looked at each other at half-time and said that wasn't the way our tournament was going to end," he told reporters.
"The commitment from every guy to keep going and do everything we could to turn the game around - for me that was the best part of it, to celebrate that with your team-mates is the best feeling," he said.
At times, Bradley's game has also included a tendency to dive in to a tackle and pick up a damaging card and he missed the final of the Confederations Cup in South Africa last year after being sent off against Spain for a late challenge.
The midfielder then had an additional suspension added by FIFA due to the way he protested the decision.
Recently though Bradley has managed to channel his aggression in a better way that avoids trouble with match officials.
"I think in any game you want to have a feel for how the ref will handle things, for the way the game is going, you don't want to put yourself in a situation where you are in card trouble or you are committing a lot of fouls that are dangerous for our team," he said.
But Bradley, who at times gives the impression of being at war with the world, hasn't lost the fire in his belly that makes him the player that he is.
"I am who I am as a player and to know that and to know what I do to help the team is important. Those things, as far as being aggressive and committed in the centre of the field, those things always have to be there," he said.
