With Everton on the back foot for large parts of their most recent match against Tottenham Hotspur, Barkley regularly had to perform a defensive role - but the England international kept his shape, and help his side claim a 1-1 draw.
Barkley’s performance in the contest may not have been his most devastating in attacking sense, but his discipline delighted Martinez.
“In my eyes, Ross Barkley’s performance [against Tottenham] was his most mature in three years,” the Spanish boss said.
“In two-and-a-half years, he’s gone from a player that had to be fitted into a structure to one that can player in different roles and master them.
“The bravery that he has, he receives the ball in every single situation.”
Barkley is generally noted for his creative ability, and he has established a reputation as one of the most exciting youngsters in England.
The 22-year-old already plays a key role for Martinez’s side, and he has accumulated 30 appearances for club and country to date this season.
Barkley forms part of Everton’s quartet of stars, who appear to have the potential to go right to the top of the game.
Barkley, Romelu Lukaku, John Stones and Gerard Deulofeu all look to be special talents, but they have not been able to drag Everton up the league this season.