Well, his selector Ray Cosgrove does anyway. Mark Vaughan, his team-mate, is more effusive in his praise of the 19-year-old he describes as “one of the best players I’ve ever seen, one of the best players I’ve ever played with”.
But Cosgrove, no stranger to impressing on the big day in Croke Park, believes he can touch up on a couple of things.
“He’s phenomenal. I was lucky enough to play with him last year. I don’t think he realises how much ability he has. I don’t think we collectively have seen the best of him.
“I think we’ve seen glimpses of it at the tail end of the League when he got a couple of goals. But from being involved as a (Kilmacud) selector this year with him... he hasn’t been quite ruthless enough, I’ll be honest.
“I think he has to take the bull by the horns a little bit more.
“He’s been very unselfish, releasing other guys ... he probably looks up to the likes of Berno (Brogan) and feels an onus to play second fiddle at times.
“But he’s more than capable of putting on a big show on Sunday himself.”
Vaughan played his last game for Dublin in 2009 and is still 28. He sees so much potency in a player who like himself was known more for his soccer attributes before lining out for the county.
“When he turns he’s gone and that’s it. It’s pretty much the unmarkable trait. If you don’t have the speed against him you just can’t put a guy on him. You’ve to alter your whole team to mark someone like him.
“You can’t just go, ‘That corner-back, he’s going to take him’. You might have to switch someone around and he’s probably one of the best level-headed guys I’ve seen for such a young lad.”
To illustrate Mannion’s groundedness, Cosgrove recounts how he turned up at a challenge game last Thursday and just kicked ball with the substitutes on the sideline — “as if there was nothing happening this Sunday”.
Dublin’s 2002 hero might feel he can improve but has no hesitation in saying he was the club’s best player last year.
He added: “His reading of the game. He makes runs; he runs into space, he’s so quick ... but he’s deadly accurate. He’s accurate from 40 yards out the field. And I don’t think that we’ve quite witnessed that yet. If he was to cut loose on Sunday, Chris Barrett or whoever is picking him up will have their hands full.”
Mannion might be quiet but there’s an assuredness in him that Vaughan knows only too well as Crokes’ other free-taker. “There was no fear of him ever (not) standing up to be counted. The county final last year. Any free, he wants to take it. There’s a fight between him and me now to take frees in our side but he’s one of those guys that just will go in, never go around saying too much.“