Sako left Wolves on a free transfer to join Crystal Palace and the Midlands side have struggled in the powerful winger's absence.
Despite bringing in Jed Wallace and Sheyi Ojo to try and replace Sako, they have still missed him desperately and Moxey admits that filling the void he has left has been tough.
“We bought two players in to replace the loss of Sako, who we could have sold for a lot of money in January but didn’t because football always comes first, so we bought Jed Wallace and Sheyi Ojo to try and fill Sako’s gap," Moxey said in the Express and Star.
“Trying to replace a player like Sako is nigh on impossible. As an example, Liverpool losing [Luis] Suarez and trying to replace him, you just can’t replace him.
“We always knew it was going to be difficult but it Kenny’s view we would replace him by doing certain things differently rather than simply buying a like-for-like replacement.
“A player like him is virtually irreplaceable unless you spend eight-figure sums and those players aren’t going to the Championship."
Sako made 124 appearances during his three seasons at Molineux, scoring 38 times and becoming a fans' favourite.
His quality made him one of the Football League's standout players, and Palace were quick to snap him up when he became available this summer.
Since moving to Selhurst Park, the Mali international has made an immediate impression and netted twice in his first three matches.
Wolves, meanwhile, have struggled in the league so far - and they currently sit in 15th place in the Championship table, with just two wins to their name.