Doubts persist over the €100m striker's future with Liverpool.
But Fowler told the Liverpool Echo: "(My opinion) is probably no different to what everyone is going to give you. With Darwin Nunez, he will score goals and he will be a handful but to what level I don't know and it is entirely up to him that, isn't it?
"And I think it is an interesting one because I think we have seen the past we play like he does but we've also seen him miss silly chances and I always think at the minute he looks tentative and he looks worried about something rather than just focusing on the chances or the runs he's got to make. I think when you're a forward, you have got to shut out the outside world if you like and just concentrate on yourself.
"What I used to do if I was having a tough time, you go back to smashing a ball and I know it is not the technical side of things that people want to hear and maybe people are expecting some technical analysis that hasn't been heard before but when you're a striker, it's not about that. It's about going back to basics.
"It's about seeing the net ripple, aiming for corners, but then all of a sudden when you're thinking of things and it gets inside your head, that is what causes the tentativeness, if you like. And that is maybe what Darwin has been guilty of this season, where he is - don't get me wrong, he is focused on scoring - but I genuinely think he is thinking of the outside world and you can't do that. If you do do that, that's a problem.
"He's got to get back to basic, start rolling balls in, it doesn't have to be immaculate. People think you've come in for £60 or £70m and people are expecting everything to be hitting the top corners. Sometimes, you've just got to roll them in to the corners, not everything has to be extraordinary.
"Was it at Brentford where he has tried to chip the keeper? If he's doing that all the time then it is bad forward play. But if he has gone around the keeper or to the side of him, that is what I mean by going back to the basics.
"The best goalscorers are the ones who do the monotony of doing the same thing over and over again. And this is like the second nature of the natural ability of goalscorers; if you're doing the same thing over and over then the game becomes easier. But if you're trying to do something different every time there's a ball then it looks unusual or unorthodox and I think that is maybe what he has been guilty of.
"He is trying too hard at times. Will he get to the level that we hope or think? I don't think that he will and that's not being a knock on him and I am not being derogatory because I would never do that, he is a Liverpool player and I want him to be the very best, but he just needs to go back to delivering what he was doing when he was younger, the basics I've seen and then not trying all the technically unbelievable, once-in-a-lifetime things. He does seem to think about things too much and I am not sure you can as a forward."