I think you’re underestimating how much of a specialised position CB is. in possession I’m sure he will fit in there fine, but out of possession? as good as dinho is, he’s a 34 year old midfielder, expecting him to perform at a world class level consistently and not just a capable fill in for a game or two is a lot to ask.
The difference here though is we were forced into the other two examples because of season ending injuries to Mendy and missing out on our primary target at the last moment last season in Jorginho. this time we’re choosing to handicap ourselves. I’m sure we will be fine for the most part of the season but all it takes is one injury and a suspension at the wrong time and were screwed. It’s a huge risk to take when we don’t have to and there’s no real benefit to taking the risk other than saving some money that we can afford to spend.