Fast forward five weeks and the Robins have the look of a team that have lost their identity.
KR's loss of form will inevitably be traced back to Tony Smith's decision to leave the club at the end of the season and the manner of the announcement.
Since making it six straight wins against Wakefield Trinity in the immediate aftermath, Rovers have failed to lay a glove on their opponents on their way to three crushing defeats.
Sensing blood after watching the Robins limp out of the Challenge Cup last week, Castleford ruthlessly exposed the vulnerabilities in the away camp.
Three tries in eight first-half minutes ended KR's challenge, the highlight another scintillating effort from the irrepressible Jason Qareqare.
Fresh from a 16-day break, the Tigers were full value for a 32-0 win that saw them replace Rovers in the top six.
It was a case of third time lucky for Castleford after two disappointing defeats at Craven Park and Lee Radford's side can look forward to the second half of the season with optimism.
For Hull KR, questions will be asked about Smith's short-term future with Willie Peters preparing to take over at the end of the year.
Optimism remains about KR's long-term prospects after Peters' first job was to convince Matt Parcell to sign a new contract, with the influential hooker joining Elliot Minchella and Kane Linnett in committing to the club in the aftermath of Smith's bombshell.
But the Robins have lost their way on the field since Smith declared his intention to move on, hitting a new low on Sunday afternoon.
In a sign of things to come for Rovers, Kenny Edwards broke clear down the left and although he was hauled down, George Griffin powered his way over later in the set.
The biggest cheer of the half from the away end came when former Hull FC prop Liam Watts was sin-binned for a high shot on Lachlan Coote, his second yellow card of the season against the Robins.
But Rovers were playing like a side that managed to score only four points in their previous two games.
One chance aside where Coote was held up over the line by Jake Trueman and Qareqare, KR did not trouble Castleford with the ball.
After losing Dean Hadley to a neck injury, it quickly unravelled for the visitors as the Tigers found their groove.
Rovers could point to a remarkable act of dissent by Jake Mamo as a turning point but that would be an easy cop out.
Mamo remained on the field despite kicking the ball out of the stadium following a decision by referee Chris Kendall and he would soon rub salt into KR wounds.
But it was Edwards' try that broke the away side's spirit, the back-rower showing fine footwork to evade Ben Crooks and touch down.
Then came Mamo's moment as he backed up a break down the right by Derrell Olpherts before channelling his inner Temuri Ketsbaia in an emotional celebration.
The best was yet to come for the Tigers, Qareqare making a now trademark break down the left before leaving Coote on the turf with a spellbinding step and racing clear to score.
With the image still racing around his head, Coote kicked the restart out on the full to compound KR's misery.
Castleford were enjoying themselves in the sun at Wheldon Road but they slowed the game down when Crooks was caught offside on his own line, Gareth O'Brien knocking over a straightforward penalty to send the hosts into half-time with an unassailable 24-0 lead.
A huge score was there if the Tigers wanted it and that looked very much on the cards when Mamo picked off Rowan Milnes' pass close to his own line and went the length of the field.
As Castleford celebrated in front of their fans, Brad Takairangi saw his first Super League outing in 10 weeks ended by a serious-looking muscle injury.
With the match long since over as a contest and the Tigers perhaps glancing towards next Friday's game at Salford Red Devils, there was an exhibition feel to proceedings as Rovers tried in vain to get on the board.
The preciously talented Qareqare had the last word, taking a superb long pass from Trueman to dive over in the corner.
Ryan Hall went close for the Robins in the closing stages but the full-time hooter confirmed a second nilling in three games as their miserable run continued.
Castleford Tigers: Hampshire, Olpherts, Mamo, Fonua, Qareqare, Trueman, O'Brien, Watts, McShane, Griffin, Edwards, Lawler, Westerman.
Substitutes: Milner, Massey, Smith, Matagi.
Hull KR: Coote, Ryan, Crooks, Kenny-Dowall, Hall, Takairangi, Milnes, Maher, Parcell, King, Johnson, Keinhorst, Hadley.
Substitutes: Storton, Litten, Sims, Richards.
Referee: Chris Kendall.