The holders, seeking to lift the trophy for a third successive season, were 40-11 ahead at half-time of Saturday’s quarter-final and, given their pedigree in this oft-derided competition, were never going to let a lead of such magnitude slip.
That Rotherham dominated the scoring in the second period, responding with three tries, did little to appease the home side, who had high hopes of making their own history at Clifton Lane.
Winger Michael Keating, the Irishman who grabbed the last of those in stoppage-time, labelled it “embarrassing” and said: “It was a massive disappointment. We’d said during the week no Rotherham team had ever got to the B&I semis and we’ve just let ourselves down.
“It was embarrassing. Lee (head coach Blackett) told us to look at that scoreboard as 32 points at home has to be enough to win any game.
“Leinster’s side were relative kids with not that much senior experience yet they played like the senior team.
“We shouldn’t be surprised as they are ridiculously consistent in this comp’ winning it for the last two years and have an electric backline with loads of pace. But it was still embarrassing.”
Indeed, the Dublin-based side have now only lost one of 23 B&I Cup contests since October, 2012 and if Rotherham fans required any reminding of their potential they need only have looked over their shoulders and watched the big screen in the clubhouse.
Brian O’Driscoll, the Leinster legend, commentated as the three-time Heineken Cup winners produced a thrilling draw at Wasps. The tyros surging on Clifton Lane are the next generation.
Fly-half Ross Byrne seemed to step up the class when his side needed it most in that first half, while two-try full-back Cian Kelleher was a constant threat.
Blackett’s side made too many unforced errors to really stand any chance of success but, after he made a raft of changes at the break, they were much improved.
Leinster were limited to just two more penalties by Byrne until Josh Van de Flier finally bundled over in the 74th minute.
Before that, Rotherham’s pressure had resulted in deserved scores for centre Lloyd Hayes and the industrious No8 Alex Rieder and Keating – who started his career with Leinster – scorched in for his seventh of the season after a quick tap penalty from 80m out.He admits, though, Leinster were too classy for them initially.
“They just have a massive focus on skills,” said the ex-Doncaster Knight. “It doesn’t matter what position on the pitch they are, they have to have those skills nailed down or they won’t play.
“You can see everyone’s comfortable on the ball and can run those plays.”
For Rotherham, they must now concentrate on the Championship and redoubling their efforts to reach the top-four play-offs.
Blackett’s fifth-placed side head to bottom club Plymouth on Saturday knowing another eminently winnable game versus visiting Jersey is to follow.
Keating realises they have to eradicate their inconsistency if they are to repeat last season’s success of making the play-offs.
“We’re disappointed in the fact we have one good result, like beating Bedford last week, backed up with a bad one,” he said.
“We need to get going again and Plymouth are improving.”
Rotherham lacked the ruthless streak of their opponents, who scored via Kelleher after just 55 seconds.
Tom Barrett replied with a penalty but Byrne dummied through to set up Garry Ringrose and then quickly found Kelleher for his second.
Barrett slotted another penalty and when Tom Denton, Leinster’s York-born lock, was sin-binned, a driving maul set up by fit-again winger Jamie Broadley.
That saw Rotherham trail just 19-11 approaching the half-hour but more mistakes saw them slip away as Bryan Byrne and Sam Coghlan-Murray each crossed and a penalty try was also conceded as the hosts failed to control a Leinster lineout near their own line.
Rotherham Titans: Scanlon; Broadley, Hayes, Davies (McKinney 40), Keating; Barrett, White (Mitchell 65); Hislop (Birch 52), Cruse (Williams 40), Tampin (Lewis 40), Maddison (Parker 40), Holmes, Argyle (Morris 40), Preece (Thiede 52), Rieder.
Leinster A: Kelleher; Ringrose, Macken (Dardis 40), O’Shea, Murray (Crosbie 80); Byrne, McGrath (McCarthy 75); Dooley, Byrne (Tracy 49), Heffernan, Molony (Prendiville 55), Denton (Beirne 67), Marshall (Coghlan 80), Flier, Timmins.
Referee: C Evans.