The youngster has certainly landed on his feet after being released by the Bluebirds in 2012, before ultimately signing for United in September following a brief spell with Newport County.
Slade was not in charge of City when Poole was dismissed, but the 55-year-old believes that such a gaffe reflects poorly on the regime at the time, and says it would never have happened on his watch.
“You set up a youth policy and academy and you don’t want to lose potential - and it is potential at that age - and quality," he told a press conference, quoted by Wales Online.
"Occasionally players get away because people develop at different rates, but clearly a decision was made at that time and they got it wrong.
“It’s something out of my control, you can’t control what happens in past - but if I was manager here at the time you’d want to know the reasons why that materialised, why a player who in three or four years time made his debut for Manchester United was let go.”
It remains to be seen exactly when and why Poole was released, with some suggestions pointing toward his size as a potential reason behind the snub.
Nevertheless, his emergence at the Theatre of Dreams is made all the more extraordinary given that he was representing St Albans in the Cardiff & District Under-15s league just three years ago.
Thursday's win over the Danish outfit also saw the emergence of 18-year-old Marcus Rashford, who was given a starting berth by manager Louis van Gaal and repaid that faith with two goals.