I am actually still pretty optimistic about this guy, but my optimism is entirely based on what I saw of him for Bologna.
This, for me, is the difference between Zirkzee and Hojlund. They've both had doubters, but, with Hojlund, I thought the doubters were being way too premature in their criticisms because, in my opinion, he showed a lot of promise almost straight away last season. He definitely had faults, but there were plenty of positives, too, so i didn't get people writing him off at all.
With Zirkzee, even though I'm still optimistic about him like Hojlund, I somewhat get the doubters here as you can't deny that there are worrying signs, and, bar a decent hour against Palace, he hasn't done much to impress. I was optimistic with Hojlund based on what I was seeing here, whereas with Zirkzee it's nearly all based on what I saw of him at Bologna, so I get the fans judging him purely off his United showings.
What I'm mainly keeping in mind is how barely anyone has looked that good under ten Hag bar Rashford's form in his first season. We're a bit of mess, so a new player who's also trying to adapt to a new league on top of that isn't going to have the best platform to perform. He very well may just not be good enough, but, personally, I want to see how he does playing under a more competent manager and in a better organised team before writing him off yet.