There's truth in what you say, but keeping our current back 4 in a 4-3-3 with a single pivot DM in midfield absolutely won't work with Frimpong at RB IMO. He's closer to being a right winger than a right back.
This is the role he thrives in at Leverkusen. He's no doubt a very good player and would be a bargain for somewhere between 35-45 million, as the reported asking fee was around that amount when we were considering a move for him over a year ago, but it would probably be way higher now, unless he has a release clause? Not sure.
My point is that expecting him to just simply replace Dalot in the current 4-3-3 we're trying is asking for trouble.