I think the issue there is that we had such a nucleus of brilliant players once Son settled that buying was never going to be easy as players want to feel they're in with a good chance of becoming a regular, and in the days of Walker, Rose, Kane, Eriksen, Son, Dele, Jan and Toby, it was tough to convince people they would not start every week when fit; even Dembele would've started every week had he been able to. I thought when the Walker thing blew up, Poch signaled to young talent out there that it WAS possible to come in and make it yours by effectively not letting Walker hold the keys and instead promoting Trippier.
There are a couple of deals which have always intrigued me (rumored I should say). DeLigt was one of them, Sancho another. Both were players we very actively wanted, and for whatever reason did not happen (in Sancho's case the rumour was Emirates Marketing Project would not sell to us) but given the remit Pochettino had, the stadium build, the financial situation and all of that, we needed to move players out that he wanted to bring the sort of young talent in he could work with IMO.
I think the only utter disaster was Janssen, and I am not entirely convinced that Poch could not have done more there - it feels like there was a clash early on and he would not let go, but I don't know the story at all.
The saddest thing is that by the time Levy half did what Poch wanted, the fractures were too great, thus 100 mill of talent only for him to be out three months later...