I was just reading a pretty good analysis of Mangiapanes' play on another fan website.
Some salient points from the article and fan comments.
Mangiapane's point are all from 5v5 play. He sees no power play time.
Playing on the third line, the shutdown line. he is always on the ice against other teams top lines with the role of trying to shut them down first, score second.
The majority of his starts are in the defensive zone.
In 2022-23, he had on again, off again shoulder problems and had post season surgery.
Often it may take a year, even for athletes, to fully recover from a surgery like this.
So, it makes it very hard to evaluate his true value I would say.