They visit Salford Red Devils tomorrow knowing another defeat – an eighth in their opening 10 games – will equal their worst start to Super League suffered in 1996.
That was the year before Sinfield began his glorious career with Leeds, going on to lead them to seven Grand Final wins before switching to Yorkshire Carnegie last autumn.
The West Yorkshire club have clearly struggled without their talisman and the former England captain admitted: “It’s been really tough to see.
“A lot of those boys are good, good friends who I played with for a long, long time.
“They are doing it tough but I have no doubt about how hard they are working and all are pulling in the right direction to fix things up.
“When you win the treble you make yourself a huge target and other sides have gone after Leeds. But I’ve no doubt over the next little while it will come good for them and the focus now just has to be on playing well at Salford.”
Sinfield’s replacement in the stand-off role, Liam Sutcliffe, has come in for some criticism this season as Rhinos struggle for attacking fluency.
The 21-year-old is only a few weeks into his return from a knee reconstruction, however, and his former colleague feels he will shine soon.
“He’s a great kid and is only going to get better and better,” said Sinfield.
“It’s been a difficult start for everyone this year but the experiences those younger players will have gained over the last 10 or 12 weeks and last couple of seasons will stand them in good stead for years to come.
“My big message to the fans, as it was when I left last year, is there might be some rocky times this season but keep the faith – they will come good at the end.”
Sinfield, meanwhile, is currently preparing for Carnegie’s British & Irish Cup final versus London Welsh at Headingley on Sunday.
He is also continuing the promotion of his book – Kevin Sinfield: My League Years in Words and Pictures – which is proving a real hit with Rhinos supporters.
“We’d done a lot of pre-orders so I wasn’t sure whether people would turn up to the actual signings,” he said. “But it’s been great seeing so many people, really surprising and very nice.
“I’m not sure how sales have gone but it was really nice to do the book because of how it all ended – us winning the treble.
“It made reflecting on it and looking back a great experience as the story concludes well.”
For tomorrow’s trip to Salford, Rhinos have lost centre Joel Moon to a groin injury aswell as second-rower Josh Walters (foot) from the side that lost against Hull KR.
But, on the positive front, forward Brett Delaney could return after a hamstring problem and full-back Ashton Golding has been named in the 19-man squad for the first time since suffering an ankle injury at Widnes almost two months ago.