The former winger, now Salford City's co-owner, expressed frustration over United's failure to regain their Premier League dominance.
Giggs believes poor decisions from the club's hierarchy have contributed to a decade of underachievement.
“Like any business, recruitment needs to be right and hasn’t been for the last ten years. We’ve just made poor decision after poor decision,” Giggs said during An Evening with Ryan Giggs earlier this week.
“Now it’s whether Ruben (Amorim) gets the players he needs, the support he needs — the time.”
The Welshman added: “We’re in a bad place at the moment but, first of all, I have to say I actually really like the manager. Given a chance and given time, Amorim will bring success back.
“If we get the right players in and the manager gets time, we will be OK. But at the moment, we are miles off it. We’re nowhere near — a long, long way behind — but it can soon turn around.”