He never developed into the natural scorer that was expected of him when he was drafted. However, for a few years he was able to establish himself as a good third line player, especially in Washington, where he won the Stanley Cup in 2018.
After the 2018-2019 season, where he had 46 points with the Caps, his best offensive production in the pros, he came with the Panthers. He had an acceptable first season of 33 points, but the following season was pretty disastrous. He had only 4 points in 21 games before ending up with Chicago, where his descent into hell really began. He had just 2 points in 10 games with them at the end of the 2020-2021 campaign.
It's not his offensive production that's lacking, but rather the state of his face, or even his morale, which seems to be at an all-time low.