The Merseyside-based club made a bright start to their season under Benitez, but have now won only one of their last four matches in the Premier League.
Despite earning just four points from their last four league games, Everton still sit eighth in the table with 14 points and are only one off fourth-placed Brighton.
However, Keys feels Benitez has brought a defensive style of football to Goodison Park and is of the view that it will not be enough for him to succeed at Everton.
Keys suggested that Benitez will have to get people out of their seats to be successful with the Toffees, but insisted that Gray, Townsend and Rondon will not help him do it like Steven Gerrard and Fernando Torres did at Liverpool.
“Just like last season, Everton had made a good start, but what we saw Sunday won’t do – and I’m afraid there are going to be many more days like that under Benitez“, Keys wrote on his blog.
“Truth is Everton aren’t very good, but playing the way he does – 7 back – 3 up – won’t do, unless he gets people out of their seats.
“Two of the three he allowed freedom at Liverpool – Gerrard and Torres – set Anfield alight.
“I’m afraid Gray, Townsend and Rondon – why on earth did Everton sign him? – won’t.“
While Keys believes Benitez will struggle to succeed at Everton, the Spanish tactician will be looking to bounce back and lead the side to a good finish in the table this term.