Zbynek
Jarry friggin sucks dude
Jake Guentzel is the best winger Sidney Crosby ever played with (not including 20 games of Marian Hossa). He's the best homegrown product the Penguins have pumped out in 20 years.Koivunen is a boom-or-bust player, and that's due to his skating. If he brings his skating up enough, his ceiling is a top-line forward. He has all the other relevant skills.
Jake is a bonified ppg 1LW and has continued to prove that with 2 other teams. Crazy tenacity, hockey IQ, plays bigger than his size, and reads the game about as fast as a Crosby or Kucherov.
Koivunen is the most valuable piece in the Guentzel trade (if you can even use that word here, valuable). Your description of Koivunen is not the return you expect for a player of Guentzel's caliber.