Few rugby players are as frustrating as Dylan Hartley.

Undoubtedly he's a huge talent - robust in the tackle, a reliable thrower and a physical ball-carrier, not to mention a fine leader. But there's also the other side of Hartley - the side that was on display in last season's Premiership final as he was red-carded for a verbal barrage on referee Wayne Barnes.

Short term, the hooker's choice language cost Northampton dearly, but long term the pain will all have been Hartley's. The incident not only meant his side had to play more than half the final a man short when already behind on the scoreboard (they duly lost 37-17), but the 11-week ban that he received was the latest in a series of disciplinary hiccups that have cost him at key moments in his career.

This one cost him a place on the Lions' victorious tour of Australia, while others (26 weeks for gouging, 11 for biting and two for punching) have stalled his England career badly.

A surprise pick for the Lions' tour in a position of relative weakness, Hartley was replaced by Ireland's Rory Best, who struggled throughout the tour, while his England team-mate Tom Youngs, who Hartley claims he was shouting at in the Premiership final, not Barnes, and Welshman Richard Hibbard shared the Test match duties.

Had he been available, Hartley would surely have been in contention for the Test starting berth after a fine end to the season, when his leadership played a key role in dragging Saints to the final.

Despite his fine end to the season, Hartley was forced to sit on the sidelines as Youngs enhanced his reputation down under and Rob Webber put in fine performances as England won convincingly in both the Test matches on their tour to Argentina.

This is a perfect example of the Hartley quandary: a strong leader and excellent player who lets himself and those around him down at key times.

Hartley has, to the dismay of some, retained his spot in England's EPS squad and has kept hold of the Northampton captaincy. Both sets of coaches have admitted that they came very close to discarding him and he heads into the 2013/14 season aware that another slip-up could cost him both. 

The New Zealand-born hooker has undoubtedly been contrite in recent weeks when expressing his gratitude to both Jim Mallinder, his coach at Northampton, and Stuart Lancaster, England's head coach for their faith in him. 

"I'm extremely thankful for the chances I've had with various coaches. With Stuart Lancaster and Graham Rowntree at England, and Jim Mallinder here, there are loyal people sticking with me. I can't let them down", he said.

2013/14 is a defining season for Hartley. Aged 27, he is no longer the tearaway tyro that was an unhinged animal on and off the field; he should be in his prime and is a senior player for both club and country - only Toby Flood of the current EPS squad has more than his 43 England caps - and must begin to show that he recognises these responsibilities. He can afford no more skirmishes with the citing commissioner. 

Despite his 43 caps, Hartley has never truly nailed down the hooker's berth for England. This is partly down to his aforementioned disciplinary struggles and partly down to his form on the biggest stage.

His dominance at club level has never truly translated to the international stage - he has failed to fend off the challenges of first Lee Mears and Steve Thompson and now Youngs (a hooker for just three years) for the No. 2 jersey.

At 27 he should be playing some of his best rugby and injury-permitting, hooker should become one of England's strongest positions, with Youngs, Hartley and Webber all competing for the shirt.

This strength in depth also means that one more slip-up could spell the end for Hartley. Lancaster has gifted him, however, one final chance to show his worth for his country and Hartley, a natural fighter who never gives up, is unlikely to take this opportunity lightly.

At Northampton, Hartley also faces a key season. Mallinder chose to stand by his captain, despite calls from fans and the media alike for him to be replaced by his England team-mate Tom Wood or stalwart flanker Phil Dowson. 

Saints have a new-look side this season (and arguably the Premiership's strongest summer signings) and are looking to capitalise on their strong end to last term. They have lost legendary flankers Soane Tonga'uiha and Brian Mujati to Racing Metro but welcome Lions star Alex Corbisiero and Wallaby Salesi Ma'afu to replace them, while they fended off interest from several French clubs to secure the services of George North, the most sought-after talent in the Northern Hemisphere.

Problems remain in terms of creativity in the backline but Stephen Myler looked ever stronger at 10 last year and the addition of Kahn Fotuali'i to compete with Lee Dickson at scrum-half should help provide flair. With a pack possessing the physicality of Hartley, Samu Manoa, Courtney Lawes and Calum Clark, they are a force to be reckoned with.

Hartley stands at the centre of exciting times for both his club and his country, but one more false step and it could all be over for him. Despite letting so many people down, his ban this summer will have hurt no-one more than Hartley himself. Since being reinstated by club and country, Hartley has made all the right noises and he will need to channel this positivity into the coming season, concentrate on his rugby and remain on the straight and narrow.

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