A season that started all the way back at the beginning of August reaches its conclusion this weekend, although 10 months will turn to 11 for those going on the tours by the Six Nations countries this summer.

It is, on the surface, asking too much to expect Harlequins and Leicester, who meet in Saturday's Aviva Premiership play-off final at Twickenham, and Leinster and Ospreys, who will battle for the RaboDirect Pro 12 crown in Dublin the following afternoon, to mark the end of the campaign with a kaleidoscope of colour.

Lip service has been paid over the years to the subject of player welfare, but as governing bodies and organisations ask more and more of those who attract spectators to grounds, and sponsors and broadcasters to part with their money, rugby in Europe is in danger of providing more and less at the same time.

Both finals, even so, have the potential to mark a fitting end to the campaign. Harlequins and Leinster have led from the front for most of the season, finishing at the top of their respective leagues, while Leicester, especially, and Ospreys were strong in the second half, although the Welsh region had an unbeaten start during the World Cup.

Harlequins and Leinster have both come a long way since their Heineken Cup quarter-final meeting at the Stoop in 2009, a match which became known for an attempt by Dean Richards, then the director of rugby at the London club, to engineer victory in the dying minutes by getting one of his players, Tom Williams, to fake a blood injury and allow a goal-kicker, Nick Evans, to return to the field.

Leinster were leading 6-5 at the time. They were then known in Europe as the nearly men, falling short when it mattered. Had Richards's ruse worked, and not been rumbled, which it may have if Williams had grimaced with pain on his way off the field rather than winking, Leinster might not have just celebrated their third Heineken Cup triumph in four years; the hard-fought victory three years ago marked a turning point.

The affair precipitated several departures from Quins, who under Richards were re-establishing themselves after a season in the second tier. It led to the appointment of Conor O'Shea as director of rugby and under him the club has flourished, making the play-off final for the first time.

O'Shea did not tear up everything and start over – he merely added to what was already there. If they play a more expansive style than most other sides in the Premiership, they are also more durable. Leicester used to be able to impose themselves physically on Quins, but the battle up front on Saturday looks even.

It may be Quins' first appearance in a play-off final, but O'Shea is determined to make it the first of many. He has more than once in recent weeks cited Wasps in the 2000s as a template, both in the way they appreciated the demands of the play-offs before anyone else, peaking at the right time and giving the players more rest and relaxation as a season approached its end, and in the tight bond within the player and management group. Once a Quin, always a Quin.

Leicester are appearing in the final for the eighth consecutive season, a remarkable record given the clutch of players they lose to the international game for at least three months every campaign. If they are hard to beat in semi-finals, they are less sure when confronted by the final hurdle having lost four of the seven play-off finals and their last two Heineken Cup finals, although they won the LV Cup a couple of months ago.

They are the Premiership's form side, unbeaten in the league when they have had their internationals, and their recovery from five defeats in their opening six matches was the stuff of dreams. They won away to the other three clubs in the play-offs in the run-in, and their victory at The Stoop came after they had twice trailed in the opening half by 13 points.

Quins looked shattered at the end of that game, although O'Shea maintains they had not emptied their tank. He took his squad to Abu Dhabi last week to allow them to wind down after the semi-final victory over Northampton, a time when his opposite number, Richard Cockerill, was waging a war of words with the England head coach Stuart Lancaster over the fitness of the outside-half Toby Flood.

Cockerill likes to keep a tight flow on information, one reason he is disdainful of Twitter, but Leicester's approach on the field has been far from tight in recent months, the midfield axis of Flood and Anthony Allen giving them a multi-dimensional approach. George Ford seamlessly replaced Flood against Saracens in the semi-final, but as Ulster's young outside-half Paddy Jackson found in the Heineken Cup final last weekend, experience counts in a final.

That would give Leicester an advantage, but two years ago they needed a late try to overcome Saracens, who were then making their first appearance in the final. The Tigers will start as favourites, but Cockerill, as impressive in his very different way as O'Shea, will have reminded his players that means nothing: they have been bit by underdogs too often in the past.

Ospreys, like Leicester and Harlequins, failed to make the knockout stage of the Heineken Cup, timidly succumbing to Biarritz in their final group match. A few weeks after that reverse, they changed their management team, promoting Steve Tandy to head coach, even though they were then second in the Pro 12, where they were to finish.

Ospreys, like Leicester, are playing with gusto, as they showed in their 45-10 victory over Munster in the semi-final. While more than 80,000 spectators will be at Twickenham, the Pro 12 final will be played at the RDS in Dublin rather than the Aviva Stadium, the venue when Ospreys won the title in 2010.

If the players will not be at their freshest there still promises to be drama, as the end of the football season showed. Never mind the play-offs, the top two in each league will do battle. Leicester and Leinster are fancied, but so were Bayern Munich.

Exiles remain outside looking in

London Welsh gave a spirited response at Cornish Pirates after learning that they would not be allowed to take their place in the Premiership should they clinch the Championship title.

The Exiles were playing for a prize they could no longer claim, but they ended a run of three successive matches without victory over the Pirates and three straight defeats at Mennaye Field. They take a 16-point advantage to Kassam Stadium next week and have the right to appeal against the RFU's ruling that they failed the Premiership minimum standards criteria.

London Welsh can wait until after the second leg to appeal, when they will know whether they are the champions, and they issued a strong statement in the hours after the Union's announcement without committing themselves to a course of action.

The RFU said that the auditors found there were various failures of the criteria by Welsh, but cited only one, primacy of tenure, the old favourite of keeping Championship clubs out of the top flight. It is a rule which effectively says that it may not be enough for Championship clubs to have the same facilities as sides already in the Premiership.

Sale are moving out of Edgeley Park, but it would have been interesting to have seen whether a Championship club proposing to share the ground with the Sharks would have passed the minimum-standards criteria. It would have been a push.

There are two problems for London Welsh over primacy of tenure. The first, and the one which snared Rotherham 10 years ago, is whether the heads of agreement they signed with the owner of the Kassam Stadium to play at the ground next season was legally binding.

Welsh, like Rotherham in 2002 with Rotherham United, signed a heads-of-agreement which stated that they would have a contract to play at the ground in the event of promotion. Would it have been enough to ensure that if someone else offered to pay more rent to hire the Kassam Stadium, they would be turned down?

The second issue was London Welsh's nominated back-up ground in the event of their being unable to fulfil a fixture at the Kassam Stadium because Oxford United FC had rearranged a match on the same date. The second stadium had to be within 30 miles of the Kassam and in Welsh's case it was not, with Brentford believed to be their destination.

The feeling that primacy of tenure is a convenient option is swelled by the experience of Bristol in the past. They have never been denied promotion, even though they play at a ground owned by a football club. Their second stadium, Ashton Gate, does meet the requirements, but Bristol are Premiership old boys, with a share in Premiership Rugby.

London Welsh have never been in the top flight and perhaps the greatest anxiety over their promotion is not just whether they would have had the money to allow them to assemble a squad capable of competing in the Premiership, but whether they would have saddled themselves with debt.

Would that be a fair reason to deny a club what it has earned. The RFU would probably back any move to simplify the criteria, and make them appear less a restraint of trade, but it has to convince Premiership Rugby. What happened to London Welsh on Wednesday does little for the reputation of English rugby. If Exeter had not owned Sandy Park would they have been allowed up two years ago? They have hardly disgraced the elite.

There is a lack of transparency. What passes as good enough for those in the Premiership should apply to those aspiring to join. The criteria should amount to no more than those of the existing Premiership club with the worst facilities.

• This is an extract from the Breakdown, our free weekly take on the world of rugby. To ensure a copy arrives in your inbox every Thursday, sign up here.