Their form before the new year in the Guinness PRO14 was sublime, they won ten of 12 in the league and effectively wrapped up top spot in Conference B.
But ahead of their semi-final against Munster on Saturday, the boys in blue need to arrest something of a slump by their exacting standards.
There is no shame in losing to Saracens in a European final but in the league they have slipped up in four of their last nine league games and have no PRO14 win since the first day in March.
But their big guns are back and they mean business domestically in defence of last year’s crown.
So how did they get to top spot in Conference B and the bookies favourites to do it all again at Celtic Park?
PATIENCE IN POSSESSION
First things first, Leinster are a team that look to retain possession and build the pressure up gradually until the dam finally bursts.
According to Opta, they carried the ball 3277 times in the league this year, an average of 156 a game which is comfortably the most of any team in the Guinness PRO14.
— Leinster Rugby (@leinsterrugby) May 13, 2019
They also have the best ruck success at 98.3% – meaning they carry more than any other team and turn it over less than anyone else.
Munster can expect a long day in defence if they are to claim a first win at the RDS since 2008.
X-FACTORS OUT WIDE
As well as their incremental carrying approach, Leinster also have the magic to break a game open in an instant.
James Lowe and Jordan Larmour on the wings are serious threats who can beat a defender in a phonebox.
And overall, Leinster have beaten 503 defenders in the league this year at 24 a game. That is the second most in the competition and matches their tally of 439.7m made per game, again the second most in the league.
BACK TO BASICS
But for all their attacking class, their fundamentals remain watertight.
Defensively, only Ospreys finished the season with a better tackle completion rate than Leinster’s 89.9%.
And in the set-piece Leo Cullen’s side remain well drilled. Their lineout success rate of 89.8% is fourth while their lineout steals tally of 21 is third.
Throw in their impressive goalkicking (77.7%, fourth overall) and it is hard really to find a weakness in the Leinster armour.
The Guinness PRO14 Final is one of the most entertaining games in the rugby calendar and takes place in Glasgow’s Celtic Park on May 25. Tickets start at just £25 for adults, £1 for kids. Visit www.pro14rugby.org/finaltickets