The industrious second-row was at the heart of a magnificent rearguard action as they overcame Castleford 38-6 on Friday night.
Such a steely performance was a welcome sight given it was the first time in 11 games they had not conceded 20 points or more.
Indeed, worryingly, the Super League champions had only managed to achieve that feat in eight of their 29 fixtures all year, their defensive quality rightly brought into question after consistently yielding high scores.
But, following an extensive examination by a Castleford side that had countless try-scoring opportunities, Jones-Buchanan feels they have now demonstrated they are regaining some much-needed resilience.
"It was a big thing for us this year," he said.
"We've probably let too many points in and our points against isn't very good.
"Going into the business-end of the season it's something that we've really got to work on.
"We're pretty confident in attack and have some dangerous attacking players but we've leaked too many tries and Friday was a good opportunity to try and put that to bed."
Leeds – who are still in the hunt for a top-four finish and face Warrington Wolves in the Challenge Cup final on August 28 – almost nilled an opponent for the first time in 2010.
Steve Snitch did finally breach them with eight minutes remaining but Ian Kirke showed their unquenchable desire by producing a terrific cover tackle on Castleford winger Kirk Dixon with just seconds remaining.
"Everybody's got to put their penneth's in, work hard and do those selfless things," added Jones-Buchanan.
"There's a lot of trust within the team and trust in each others' roles so when people make a break we've got to show that desperation in getting back.
"We're playing finals football now with the play-offs coming up and the Challenge Cup in a couple of weeks, so we have got to get back to these real big defensive efforts."
The 29-year-old, who enjoyed his testimonial season at Headingley last year, reckoned it was their finest defensive display of the campaign.
"Cas love attacking," he said, "They've some dangerous plays off Ryan McGoldrick and Rangi Chase but we showed a lot of that desperation."
Meanwhile, Leeds prop Jamie Peacock will undergo a scan on his injured knee today after hobbling off on Friday night putting his final place in jeopardy.
However, Jones-Buchanan believes the talismanic England captain, who has already shown immense powers of recovery to battle back from an ankle injury in time for the quarter-final against Wigan, will be fit for Wembley.
"JP's one of the toughest blokes I know," he said.
"He's like the Black Knight on the bridge in Monty Python; even with no legs or arms he'd still put a shirt on and I'm sure he'll be there."
Forward Luke Burgess is set to miss the final though after breaking his jaw at Castleford.