Button said Kakko reminds him of Florida Panthers forward Jonathan Huberdeau and Hughes is reminiscent to Hockey Hall of Famer Steve Yzerman.
"Yzerman was 5-foot-10 and 155 pounds when he was drafted (No. 4 in the 1983 NHL Draft) by the Detroit Red Wings," Button said. "He was just this little centerman from Peterborough. I think the Red Wings thought they were going to get Pat LaFontaine, but he went one pick earlier (to the New York Islanders), so they got their man at No. 4."
Hughes (5-foot-10, 171 pounds), No. 1 in NHL Central Scouting's final ranking of North American skaters, averaged 21:00 of ice time in 50 games and had a team-leading 112 points (34 goals, 78 assists). He set NTDP records for assists (154) and points (228) in 110 games in two seasons with the program.
Kakko (6-2, 194), No. 1 in NHL Central Scouting's final ranking of International skaters, averaged 18:11 of ice time in 45 games for TPS, scoring 38 points and leading the team with 22 goals despite being the youngest player on the roster. His 22 goals set a record for a first-time draft-eligible player in Liiga, one more than the 21 Aleksander Barkov had for Tappara in 53 games in 2012-13.
"Kaapo is going to have to wait for the puck but Jack's going to have it," Button said. "To me, the player that has the puck more and can have more of a free-skating game, instead of playing on the wing, is going to have more of a chance to impact the game. Jack does that, he does it with his mind, he does it with skating and does it with his hands."
NHL.com sought the opinion of NHL scouts who have watched Hughes and Kakko this season. They promised honesty for anonymity.