Like all first-year pros, the 21-year-old had to adjust to a different level of competition, namely facing pros older and bigger than those of the junior ranks.
"The biggest thing for me was the strength of guys and how strong they are down low," Gropp said. "It's hard to get to the net in this league and you don't have much time with the puck. I think that was the biggest transition for me, and I think I'm still learning as I go here."
Gropp has made strides though. Jed Ortmeyer, the Rangers' Director of Player Development, said Gropp's strength is when he has the puck, but he's also improved finding the puck rather than letting it find him.
"He's at his best when he has the puck. He proved that in juniors when he put up big numbers," Ortmeyer said. "It's hard to get the puck in pro hockey, and he has to work hard to get it and work hard to be stronger with the puck when he has it. He has come a long way since the beginning of the year."
Gropp's success has been built on his play away from his own net. Entering his draft year in 2015, the Kamloops, B.C.-native was regarded as having arguably the best shot in the entire class, and he put up three consecutive 30-goal seasons, including 35 his final year in Seattle.
But in the years since he was taken 41st overall, Gropp has made it a point of improving his play in his own zone. He improved his plus-minus rating year after year in Seattle, going from a minus-5 his first season to a plus-25 in his final. He also worked extensively on the penalty kill with the Thunderbirds, becoming a player not often used in that situation to one of its most.
"That's a huge part of the game, being a 200-foot guy," he said. "If you're working hard in your D zone, you're going to have the puck way more and be able to play offense way more. That's the biggest thing I've learned and I'm still working on that."