The 21-year-old from Espoo, Finland just completed his third NHL season and was set to become a restricted free agent on July 28th. In 55 games this season, he had 27 points (8 G, 19 A), 12 penalty minutes, and was a -9.
Heiskanen is one of the brightest young stars in the game and, while the deal is rich, it closes the door on any possible offer sheet scenario and locks up a key young piece long-term in Dallas.