What should Leinster do with Sean O’Brien, Dan Leavy and their backrow dilemma?

Until he proves that he's no longer Sean O'Brien you have to believe that Sean O'Brien will still be Sean O'Brien when it's time to be Sean O'Brien.

O'Brien, a fit and eager Sean O'Brien, has been named at openside flanker for Leinster's PRO14 match with Treviso on Saturday after recovering from a shoulder injury he picked up during the province's draw with the Scartlets last month, a match which marked the Leinster flanker's first game back for the province since undergoing a small procedure on his hip in January. The Lions backrower has battled calf, hamstring, shoulder, foot and a long list of other issues throughout his career but he's somehow always found a way to recover from each injury without any significant drop in production. When O'Brien was named at blindside flanker for Leinster's 2016 Champions Cup group stage clash with Montpellier last season it marked his first Leinster appearance in over nine months. He had just recovered from a serious hamstring injury during the Six Nations defeat to France and he managed only 40 minutes in a bruising affair in the south of France. Six days later, he trudged his way through 58 minutes in a win over Connacht at the RDS. Two weeks later, he received 67 minutes in a dominant win against Canada. One week later, he played the full 80 minutes against New Zealand at the Aviva Stadium. He was Ireland's best player on the pitch less than a month after he first stepped back onto the paddock following three-quarters of the year spent sitting in the stands. Not bad. O'Brien went from not playing a game in nine months to being the best player on the park against the best team in the world in just over three weeks. That's Sean O'Brien. But given the premature endings to the careers of former teammates Luke Fitzgerald and Jamie Heaslip, there is the worry that each injury could be the last for O'Brien, the final nail in a coffin that refuses to close, but then he plays a couple of games for Leinster and Ireland and he's back to being Sean O'Brien again; the destructive, uncompromising, hard-hitting force. Leinster have been itching to get O'Brien back all year, for obvious reasons, but during his absence Dan Leavy has emerged as one of the best players in the country, albeit through a little bit of misfortune at the expense of Josh van der Flier. There's an argument to be made that you have to play O'Brien in next weekend's Champions Cup semi-final (assuming he makes it through the Treviso game unscathed), but there's also a very compelling argument to be made that you can't displace Dan Leavy from openside flanker either. Leavy has been sensational for Ireland and Leinster this season and his presence will be very much needed at the breakdown against a Scarlets team that thrives on quick ball and width, but O'Brien has that type of rare talent that could see him walk into any team in world rugby on any given day. How many Irish players could say the same? A handful? O'Brien's versatility will likely prevent any head-to-head competition from happening, but then, whether he plays on the blinside at six or whether he plays at the back of the scrum at number eight, who makes way to accomodate Leinster's two best backrowers? Rhys Ruddock was one of Leinster's best players before his hamstring injury ruled him out of the Six Nations. Jordi Murphy is having one of the best seasons of his career, and like Leavy, has benefitted immensely from the added gametime he's received through the absence of others. Jack Conan could return from a knee injury next weekend and continue his stellar campaign from number eight, while Scott Fardy, 'second row Scott Fardy', has been one of Leinster's players of the season and an enforcer in a pack that is already brimming with brutes. Potentially, there could be seven players vying for three positions in the backrow next weekend, six if Fardy moves to the second-row and Devin Toner drops to the bench. Max Deegan, as good as he's been in the limited time he's received this season, might be told his boots won't be necessary for the one game that this Leinster team have been waiting for ever since the Scarlets ripped them apart in last season's PRO12 semi-final at the RDS. Leinster are better equipped to deal with injury this season than just about any other team in Europe, but how do you decide between Murphy and Conan? How do you choose between Ruddock and Fardy? Toner and Fardy? Jamison Gibson-Park, James Lowe and Fardy? Any forward and Scott Fardy? Leinster have done a great job this season of rotating their players and spreading the workload about as evenly as can be expected for a squad with their level of talent and depth, but Treviso should serve as nothing more than an audition for the final few support roles in what should be Leinster's biggest production of the season. The presence of John Barclay, James Davies, Aaron Shingler and Tadhg Beirne for the Scarlets may force Fardy into the second row, but it still essentially leaves Leinster in a situation where three players are fighting for the one role. With the caliber of players competing for the positions there really is no wrong answer, just the difficulty of finding the right solution in a team that can seemingly do no wrong... until the semi-finals at least.