England have lost six out of nine games this year, including a 2-1 series defeat to South Africa in June.
They also finished fifth in the Six Nations, which they entered as champions.
"I would never underestimate his ability to turn things around, very, very quickly. He's been around for a long time, and knows how to reinvent himself and tweak things within a team," World Cup winner Eales told the BBC.
England's slump has come as a shock after an fine run since Jones' appointment in 2015, which included 18 consecutive test wins and two Six Nations titles.
"He demands high standards, so I can imagine the intensity of that environment will be difficult to maintain over a long, sustainable period of time," Eales added.
"But there is no question England will improve. Anyone who takes England lightly is a fool. They have a lot of talent in the team and a bright guy in charge."
England play the All Blacks, South Africa, Japan and Australia at Twickenham in November.