“You know how I think they choose people for the Gryffindor team?” said Malfoy loudly a few minutes later, as Snape awarded Hufflepuff another penalty for no reason at all. “It’s people they feel sorry for. See, there’s Potter, who’s got no parents, then there’s the Weasleys, who’ve got no money — you should be on the team, Longbottom, you’ve got no brains.”
Neville went bright red but turned in his seat to face Malfoy.
“I’m worth twelve of you, Malfoy,” he stammered.
Malfoy, Crabbe, and Goyle howled with laughter, but Ron, still not daring to take his eyes from the game, said, “You tell him, Neville.”
“Longbottom, if brains were gold you’d be poorer than Weasley, and that’s saying something.”
Ron’s nerves were already stretched to the breaking point with anxiety about Harry. “I’m warning you, Malfoy — one more word—”
“How did I get the Stone out of the mirror?”
“Ah, now, I’m glad you asked me that. It was one of my more brilliant ideas, and between you and me, that’s saying something. You see, only one who wanted to find the Stone — find it, but not use it — would be able to get it, otherwise they’d just see themselves making gold or drinking Elixir of Life. My brain surprises even me sometimes… Now, enough questions. I suggest you make a start on these sweets. Ah! Bettie Bott’s Every Flavor Beans! I was unfortunate enough in my youth to come across a vomit flavored one, and since then I’m afraid I’ve rather lost my liking for them — but I think I’ll be safe with a nice toffee, don’t you?”
(Harry Potter and the Sorcerer's Stone)
Does "that's saying something" have the same meaning shown on macmillandictionary.com ("used for emphasizing that what you have said is more extreme than it seems")?