The 6ft 3ins Canadian centre is doing the job he's been asked to do in every part of the ice - and the coach says he is an example to all other Sheffield Steelers skaters.
Speaking ahead of the club's Saturday home game with on-form Belfast Giants, Barrasso indicated how much he valued the 31-year-old forward.
"John has been playing at a high level for the last few weeks" he told The Star.
"His game has been solid in both ends of the ice. He is leading by doing this. Hopefully he pulls his teammates along with him."
Barrasso is impressed with the "drive to his skating" when he is on the puck.
Armstrong will have to repeat his recent form against Giants, who won 3-1 at Fife Flyers midweek to stay on top of the league, tied on points with Cardiff Devils, who have a game in hand.
Sheffield visit Cardiff on Sunday in what is one of the most difficult weekends of the entire campaign.
Steelers are a hefty 23 points behind the top two.