The 32-year-old is a 75-test veteran for England and replaced the
injured Billy Vunipola late in the 2017 British and Irish Lions squad.
"I went up and had a chat to him (Haskell) on Saturday," Jones told Sky Sports News. "We had a good chat and at the moment he's just not playing well enough but the door's not shut on him.
"We know he's a great player and has been a great servant for English rugby, nearly 80 caps and I'm sure he'll regain his form."
Exeter Chiefs loose forward Sam Simmonds earned a first call-up and
Sale Sharks wing Denny Solomona earns a recall just two months after
being ejected from the England camp for late-night drinking.
Has Jones received any assurances that Solomona won't misbehave again?
"None," replied Jones. "He's a human being. Everyone makes mistakes,
he made a mistake, he's atoned for it and we're expecting him to follow
the team's culture which he will."
Hooker Dylan Hartley was also selected after a citing against him was dismissed on Wednesday.
Northampton Saints boss Jim Mallinder said the citing was "unjust", but Jones had nothing to say about the issue.
"That's a matter for his club to deal with," Jones said. "I think Jim
Mallinder spoke very eloquently on that so I'll leave that to him.
"We don't have an issue with Dylan at international level. That's at club level, and I don't talk about club issues.
"He'll come into camp as one of the 30-odd players and if he does well he'll be captain."
Two 'apprentice' players have been included in the squad to assist
the players prepare and they are Bath flanker Zach Mercer and Harlequins
fly-half Marcus Smith.
"You've got apprentices in your office where they make the tea and
when you need some paper they get the paper, they get the paper clips so
it's quite simple," Jones responded.
"They'll make the tea, get people's boots, put out the cones, chase
balls and practice a little bit at the right time. But they've got to
earn their stripes.
"They're the future of English rugby. Now whether their future's the
2019 World Cup will be dependent on their progress, how hard they work
and how much they keep their feet on the ground and don't believe what
you guys write about them."