The ex-Magpies star has heaped praise on the 18-year-old.
Indeed, while 'some senior players' failed to show what they are made of, Watson believes Paul Dummett, Jack Colback and youngster Armstrong stood up to be counted towards the end of the miserable 2014/15 campaign.
He told the Chronicle: "I thought at the end of the season, in the games I seen, I thought they all did well. Paul Dummett, Jack Colback and Adam Armstrong, when he got a chance, shone. They stood up and they were counted.
"Some of the senior players should have stood up but the younger lads were probably the standout performers. Looking forward that has to be a plus."
An important season?
Newcastle will no doubt continue to be linked with a new striker this summer - while one can only hope the club are actually being active in any pursuit.
But, as things stand, 18-year-old Armstrong may have plenty to do next season. Emmanuel Riviere looks as though he could have too much work to do to claw back his Newcastle reputation, while Ayoze Perez can't hold the fort alone.
Even if the Magpies do sign a big-name striker, there will be times when Armstrong is needed - be it from the bench or even from the start. He is young and needs time but may just see himself in the limelight next term.