The first time they did it, Clive Griffiths’s side had given no prior warning that they were capable of turning a bottom-four finish the year before, into second place and a berth in the play-off final.
To then back that up the following season, without the element of surprise working to their advantage, when they still finished fourth before being swept aside by Premiership-bound London Irish in the semi-final, it was seen as a tacit acknowledgment that the Castle Park outfit were genuine contenders.
Backing that achievement up for a third season, though, gets no easier, given the odds stacked against them.
Firstly, the first-past-the-post system has returned, which reduces the chance of Doncaster earning a ticket to a nerve-jangling promotion play-off scenario, when the bigger budgeted teams know a couple of slip-ups could see their promotion dreams end in tatters.
Secondly, there is the vast budget that Bristol possess following relegation, which makes them clear favourites to claim top spot and the sole promotion place.
Thirdly, the dual-registration market which Griffiths has proven a master of utilising these last two seasons, will be reduced in 2017-18 because there are more Premiership A-league games, meaning top-flight clubs will be reluctant to let their players go down to the Championship for game time.
Finally, there is the ambition of Doncaster Knights themselves, who released a statement on the eve of the play-off semi-finals last season saying they would not seek promotion if they won it, due to the finances and the improvements to their infrastructure required.
Publically, Doncaster are not saying whether they would pursue it again this season, though privately they no doubt have accepted the reality of the situation – just as neighbours Yorkshire Carnegie conceded this week – that throwing good money at promotion is no guarantee of anything, especially when Bristol have bottomless pockets.
So how does Griffiths – the great motivator – approach a season without a tangible ambition.
“To get to the top four in any league is significant, and for us to have done it twice is great achievement. That’s got to be the goal again – top four,” said the Welshman.
“If we can back it up for a third year it will be an absolutely fantastic achievement.
“Ealing and Bristol have spent a lot of money, they’ve got the lion’s share of players that are available.
“Then you’re in the queue behind them trying to attract the next crop of talent.”
Doncaster have recruited wisely. They have not shipped in and out in mass bulk as neighbours Rotherham have, or they in fact have had to do in years gone by, which points to a settled squad at Castle Park.
They are also starting to reap the benefits of their own academy, through a partnership with Doncaster College, that is now entering its fourth year.
Four players have come in from Rotherham – centre Will Owen, full-back Charlie Foley, prop Ian Williams and second-row Tom Hicks. Owen Evans drops down from Premiership Harlequins and they have signed Junior Bulumakau from Glasgow, the brother of Andy who is a fan-favourite at the club.
“We’ve got a team that we think can be competitive,” said Griffiths. “I’ve been pleased with the recruitment and what I’ve seen in pre-season.
“It (first-past-the-post) hasn’t affected our recruitment or our planning, we are still a good club for people to come and play for.
“Look at Will Hurrell two years ago going up to Bristol and WillGriff John going up to Sale Sharks last year.
“Also, the academy is vitally important for us. With the way this league is going, you never know how hard it’s going to become to secure finances and therefore players, so at some stage we are going to have to call on our homegrown talent, and some of these boys are not far off.”
Griffiths has been a vocal objector to the abolition of the play-offs, given how much excitement they have created around the club and the town over the last two seasons.
He fears that promotion could be decided by February, taking some of the external interest out of the competition.
But that is an argument for another day. Right now, Griffiths has his own team to focus on and an opening date at Jersey today.
“For us, all we can do is look at trying to finish in the top four again,” he said. “The bare minimum, as always, is to maintain our Championship status.”