Armstrong's exploits have caught the eye, despite Blackburn's struggles in the second half of the season, and his second treble in three outings left him with 29 goals for the campaign – the first player to score that many league goals for Rovers since Alan Shearer.
Ben Brereton's second in as many Ewood outings put Blackburn ahead before the break, only for Lukas Jutkiewicz to equalise with a header five minutes after the restart.
But Blackburn pulled away, with Armstrong lashing beyond Connal Trueman, before a sumptuous Harvey Elliott finish made it four, and it was fitting that Armstrong ended the season by recording a second successive Ewood hat-trick.
Rovers finished the season with 10 points from the last 15 available and after the game, Mowbray was philosophical about his star striker's future.
He said: "He could have had 40 rather than 29 but that's okay, that's good that he's thinking like that, that he's disappointed he hasn't scored more.
"For Adam's sake let's hope the phone rings and someone offers us a ridiculous amount of money, we shake him by the hand and we say 'go and bang in loads of goals in the Premier League' and we'll use some of that money in the team and can find another striker who can bang loads of goals in.
"That's football, that's happened since the game started. He's shown what a talent he is, he could have had five today. My analyst is saying the first one wasn't offside but there you go.
"Let's keep rolling, see what the summer brings for Adam and the team.
"There's a few players out there at the end who won't be here next season but that's okay, every team has to evolve and grow, and develop."
They finished the season with a second successive loss – their only defeats in eight matches. And after the game, Gardner said the youthful team performed well, despite the scoreline.
He said: "We were constantly in touch with the gaffer before, during half-time, and after, and once we got safe, we had a plan and that was to give the players what they deserve.
"The younger players have had a great season with the under-23s and under-18s and we only think it's only fair to give them the opportunity they deserve, and that creates that pathway from the Academy to the first team which I know Lee wants to do.
"That big step up for them is important, and to play back-to-back game in the Championship is a real test, but I think the young players and the players that haven't had that much game time coped with it quite well because they had a strong team out today and we matched them for pretty much most of the game.
"Probably the last half hour we faded, which is expected, but it's okay."