The board have screwed us with the finances. We should have bought kounde before he went to Sevilla, but our board were too busy looking for the next Galactico. Upamecano for 40m is a good price, I believe fofana who went to Leicester for a similar price is a good buy. We spent a similar amount on lenglet.
Hindsight is always 20/20. Nobody knew Kounde would turn out so great. Some people were doubtful when Monchi spent 25m on a relatively unproven defender from Ligue 1. And 25m for a club like Sevilla was like 50-60m for us (in pre-corona times). What if we'd buy Kounde and he'd never get regular minutes behind Pique/Lenglet to show what he can do. He would never developed as much as he did in one year playing regularly for Sevilla and some fans would probably already call him another flop and be willing to give up on him. So things are not always as easy we could just say "oh, if we'd buy Kounde last year we'd be in a great positon now".
We were fairly criticised for ignoring a CB position from 2011-15 first hoping Puyol will suddenly come back from injuries and then by signing Song to turn him into a CB
followed by Zubi buying injury prone Vermaelen and old Mathieu to save our problems (though tbf Mathieu did quite well). But I think we did better since 2016. Umtiti was a great signing before his injury and Lenglet also a pretty good imo. Remember he was brought to be Umtiti's backup but had to become a starter. So what really set us back was Umtiti's injury. If he would stay healthy and in his pre-injury form we would be in a much better position right now with Pique, Umtiti, Lenglet and Araujo.
We were also constantly looking for cheap "gambles" at the position both for the first team and Barca B with Marlon, Mina, Todibo, Araujo, Cuenca,... so it's not like we didn't try. Sure, they didn't make it and were sold for a profit althugh Araujo still has a chance to stay here longterm at least as a backup. But of course it would be better if instead of spending that Neymar money on 100m attacking players we'd buy VVD (and we probably wouldn't need to spend as much on him as L'pool did) and use the rest of money for Mane/Salah and a good midfielder or two. Fabian Ruiz was available for 15m first and 30m later for example. I don't know if he'd make it here but he'd certainly be worth a risk for either of those prices.
But again, it's easy to say what should've been done different now. At the time we've signed Dembele and Coutinho people thought while they were overpaid they will still turn out good (and if they would nobody would care about their price). Signing a young CB from Sevilla (where we always bought good players from) to be a 3rd CB was also a reasonable decision. While Lenglet is not world class we still got a durable (which is important given a lot of our other recent younger signings had injury/fitness concerns) and mostly dependable player for the last two years or we'd probably look even worse. Yeah, ideally he should be a 3rd CB which is what he was bought for initially but he's far from our biggest problem imo. We shold still look to upgrade him in future but for now our priority should be to find Pique's successor.