Yes that's what I'm getting at. He's nothing special on the ball and you don't go from that to Marcelo, Trent, Shaw, or anywhere close to it. He's also not Hakimi or Davies or anything special speed wise, and that doesn't change much either. He's generally decent all around without anything else. I remember Darmian got praised when he first joined, Wan Bissaka, Dalot went through good periods... To be honest i see more talent on the ball in Dalot than I do in Dorgu, and Wan Bissaka had his unreal recovery tackling ability.
So if you look at our squad now, of course he improves it. He's a left back who is fit. If you look at where do we want to get to, will he be starting then? Does he have that level in him? Of course potential is unknown, but I don't think he'll reach the level of someone like Shaw who he is essentially replacing, so in that sense it's a downgrade.