He was pretty solid in the defensive zone, but didn't do much in the offensive zone. I think he was benched most of the third period when team Czechia tried to protect their lead.
I wrote this to the Devils forum earlier today:
I don't know what to think about Jiricek. It seems that his puck skills and skating aren't particularly good. Maybe this is a hot take and I significantly underestimate him, but he reminds me of a former #3 pick Zach Bogosian. Both are big guys who have pretty similar skating styles. Maybe Jiricek have more skill than Bogosian, but I haven't seen much of that in these few games. The biggest difference for me is that Jiricek is much more agile than Bogosian, who always looks slow and clumsy, and he has also more accurate shot.
I expect that Jiricek will be a better player than Bogosian, but I think they have some similarities in their game.
I have to add that I'm not a prospect expert, so take it with a grain of salt.