Not sure why you're comparing Dumba to Tucker, Roberts and Clark since he is a defenseman.
Button is an intelligent guy, he can just fall in love with a player and let that make up his mind for him. He's a great scout, great hockey mind, but he's not GM material, he's a scout through and through.
Not as players, as their impact to a team. The guys I cited had an intangible that cannot be measured on a stats sheet. This is what Dumba can bring to this organization.
Don't want to turn this into a Button thread, but it has been well documented before Button was the guy that let Martin St Louis go for nothing, among other questionable moves of giveaways under his pro scout/GM days ie. Marc Savard, Alex Steen, Giguere, and his extreme love for Fabian Brunnstrom.
So if history is a precursor, don't take his opinion too highly folks. Ie. Galchenyuk is the next Ron Francis.
The Hossa comparison is the strongest one, in my opinion. You can actually confuse the two from how similar they skate and stick-handle.
One thing that cannot be measured, Hossa has a lot of hockey smarts. Does the small things very well. You can even say when he left Ottawa he took his game to an even higher level playing with guys like Toews, Kane and Sharp where he is not the main focus.