Well that was a remarkable weekend of rugby. Irish rugby fans were treated to the good – Paul O’Connell’s totemic Heineken Cup return at the Stoop – and the bad – an Ulster loss featuring another Luke Marshall blow to the head – with Leinster throwing in some basketball rugby for the Friday night appetiser.

Scoring 48 points against any team is a pretty good night’s work, but Leinster’s coaching team won’t have been happy with the defensive work on show at Adams Park in their Amlin quarter-final against Wasps. Leinster missed 18 tackles on the night, the highest total of any of their European matches this season and especially bad considering the team are the owners of the best mark in the Heineken Cup this year, the astonishing 99% rate in their opening match of the campaign.

Wasps and Leinster threw the ball around like both teams had quietly agreed that none of them would be getting on a plane to Australia if it was a 9-6 snorefest. Christian Wade was dazzling with Tom Varndell merely dangerous. But after that opening flurry Leinster stepped things up a notch and opened up like they have done precious few times this season, especially away from home.

Sean O’Brien had a big all-round day, making 10 carries and 12 tackles without a miss. Ian Madigan popped up with 51 yards on the ground (of Leinster’s backs nobody attempted more carries) and notched up 28 points. Madigan has now scored 68 points in three games, serving very public notice to Jonathan Sexton that he’ll have a fight on his hands to reclaim the number ten shirt for his pre-Parisian swansong.

Leinster will return to the RDS to face a Biarritz team who outlasted Gloucester 41-31 in Kingsholm in a match that made the Leinster and Wasps defences look positively watertight. Between them Biarritz and Gloucester missed 57 tackles on the night – FIFTY SEVEN – leading to 19 line breaks.

But on to the main events on Saturday and Sunday.

By 5.30pm on Saturday evening Clermont had booked the first of the four semi-final places, disposing of a tough and organised Montpellier team (in order to play their semi-final in Montpellier, as it turned out). Clermont’s combination of power and pace eventually broke down Montpellier’s defences, with moments of inspiration from Morgan Parra, Wesley Fofana and the magnificent Sitiveni Sivivatu making the difference.

An hour later, Ulster strode onto the Twickenham turf and despite dominating possession and territory could not make it count. Going into the game, Ulster had been the worst lineout in the competition with just a 75% success rate. Amazingly, they made this average even worse, coughing up six of their own throws for just 60% on the day. The Saracens set piece was perfect, 17 from 17 from scrum and lineout and just one missed kick on the day.

Courtesy of some late rampages from Iain Henderson and late substitute Stuart Olding, some of Ulster’s stats with ball in hand were eye-opening. In any of their six previous games Ulster had beaten a maximum of 17 defenders; on Saturday Ulstermen left 34 trailing in their wake. Only Toulon have managed to equal that in any match in this season’s tournament. But it was too little, too late. In NFL parlance it was the equivalent of a team well behind in the game getting “garbage time yards” as the comfortable winners took the foot off the pedal.

More than a few of those who attended that Saturday evening letdown (from an Irish point of view) might also have gone along to next door’s Twickenham Stoop for Munster’s titanic battle with Harlequins on Sunday afternoon. While much has and will be written about Munster’s passion, the return of Paul O’Connell and ROG shaking off two early misses to land a subsequent six from six, some of the stats from the game are quite astonishing when one considers the form the two teams had been in.

Harlequins had come into the quarter-final with a penalty differential that was simply silly in its vastness. The London club had conceded just 7.8 penalties per game thus far, 9.5 fewer than their opponents per game. In contrast, Munster had conceded 13.5 per game, almost three penalties more than they’d managed to be awarded themselves. Sunday would come as a sharp shock to Harlequins as they were pinged 14 times to Munster’s 11, a figure that might come as a shock to some Munster fans who were outraged at referee Jerome Garces’ handling of some early scrums.

Led by Tommy O’Donnell’s 13 tackles, Paul O’Connell’s men tackled their hearts out at a 98% clip, again their best mark in the competition this season. Only two teams in this Heineken Cup bettered Munster’s 81 tackles from 83 attempts; Castres (by a whisker – 82 from 84) and that amazing Leinster effort against Exeter at the RDS (138 from 140). That one of the two tackles missed was by Ronan O’Gara would perhaps be predictable, but the veteran fly-half balanced his defensive ledger with key involvement in two choke tackles that resulted in turnovers.

O’Connell’s impact was immediate in the lineout, coming up with an early steal from a Harlequins throw and generally making life extremely difficult for 21 year old hooker Rob Buchanan.

Munster won 96% of their rucks (beating their previous best of 94%) and conceded just 11 turnovers, the lowest number of any team on quarter-final weekend. As an aside, Paul O’Connell himself will surely have noted his three turnovers conceded; even in a towering performance putting him squarely in line for a Lions place and possible captaincy there’s always room for improvement.

As Rob Penney and the coaching team review the game they’ll probably be disappointed with their inability to get over the whitewash. In a six point game, Munster’s second half twenty-minute opening onslaught really should have put them further into the lead. Against a team like Clermont, kicks alone probaby won’t get the job done.

But Penney will have been very satisfied with what Harlequins didn’t do. Munster restricted Conor O’Shea’s team to zero tries, 12 points, two line breaks and just two defenders beaten – all season lows for Quins in the tournament. A stunning performance.

Toulon wrapped up the last Heineken Cup slot with a tight win against a Leicester team who did what few teams can do – disrupt Toulon at the set piece. Going into the day Toulon had secured 94% of their own ball at scrum time while their opponents had managed just 72%. On Sunday those stats were almost precisely reversed.

Leicester fans will point to their having to play the match with 14 men for 20 minutes with both Toby Flood and Dan Cole receiving yellow cards for deliberate knock-ons but missing 24 tackles to Toulon’s 13 might have a lot more to do with it.

One small strategic point, in what should have been the final phase of the game referee George Clancy awarded Toulon a penalty advantage deep in the Leicester 22 as the clock ticked into the 79th minute. Play kept going and 20 seconds later Johnny Wilkinson kicked a drop goal to finish the match “with a flourish”, as the Sky commentators put it. But did Wilkinson and Toulon make the right decision?

Toulon had been three points up at the time. The penalty advantage was awarded at precisely 79:00 and the drop goal was kicked with the game clock showing 79:21. A kicker is permitted to take 60 seconds for a penalty attempt on goal from the moment a team elects to kick at goal; the penalty was in the 22 so even a scuffed Wilkinson effort would have easily gone dead. A kicker with Wilkinson’s skill could even have taken an unlikely rebound off a post out of the equation by simply kicking it very, very high. As long as the ex-England fly-half used a goodly amount of the minute he would have been allocated and taken his place kick after the game clock had ticked past the 80 minutes as long as the ball went dead it would have been goodnight Vienna.

As it was, the drop goal was scored with over 30 seconds remaining on the game clock, allowing Leicester to take the ensuing kickoff and have a chance, albeit a very slim one, to claim the kickoff and perhaps score a converted try to steal the match from under Toulon’s noses.

Was it extremely likely? No. Do rugby players go around with stopwatches around their necks? Of course not. But this is the world of professional sport, and if it had the match had instead ended with Toby Flood kicking a match-winning conversion the Toulon players would rightly have been questioned for why a side brimming with so much World Cup winning experience didn’t simply play out the clock.

But enough of strategic nit-picking. Thoughts instead move to Montpellier and back to Twickenham with Leinster again playing the Amlin appetiser in the RDS while the brave Ulstermen dream of what might have been.

Munster will doubtless be bottling whatever it is that provided Sunday’s performance; Clermont fans will be trying to physically move the Stade Marcel Michelin to Montpellier brick by brick to avoid a repeat of their last semi-final defeat to Leinster in Bordeaux; Toulon will have their cast of elderly statesmen on several drips and perhaps Saracens will find some way to lose all their recordings of their appalling “music” relentlessly pumped through the PA system of whatever stadium they happen to be in at the time.

The rich tapestry of the Heineken Cup gained another few special threads this weekend.

Long may it continue.

N.B. all stats courtesy of the good people of the Amlin Opta Index and ESPN.

Correction: a previous version of this article incorrectly referred to the Leinster/Wasps match as a semi-final. This error has been corrected.