National Football League Overview: Mickey Harte is something of a patron saint to the Allianz National Football League.

It was the Tyrone manager who in the wake of leading his county to a first All-Ireland in 2003 revealed his team had trained collectively only twice a week. He then openly endorsed the league title - an achievement not normally uppermost in the thoughts of a first-time All-Ireland winning manager.

"The other interesting statistic," he added, "is that yesterday was our 21st match and we never played a single challenge in the entire year. I think it's very valuable to be playing in the National League up to the concluding stages."

It is a measure of Harte's influence that this view of the National League's desirability has become commonplace. In the past a successful spring campaign was regarded as something of a jinx whereas now it's a credential for the championship.

If Tyrone have popularised the concept the reason for the league's rising importance lies in the structural reforms implemented by the GAA earlier this decade.

For a start the calendar year season means that the National Football League has become a definite progression towards the summer rather than an unwieldy, meandering competition that got in the way of championship prospects.

Secondly the arrival of the qualifiers and the extended fixture list has meant that the old rhythms of big build-up to all-or-nothing matches have had to segue into a steadier beat of consistent and regular performance.

Take Ulster for instance. The province's visceral rivalries and dogged competition left league winners particularly vulnerable to ambush once the championship began.

Tyrone in 2003 were the first northern county in 35 years to do the double.

Since the new seasonal structure was established five years ago, the best teams have been featuring in the latter stages of the league.

In the 10 years up to 2001 just one team, Kerry, managed to win league and All-Ireland double and seven league winners didn't even add a provincial title.

In the five years since, there have been two doubles plus an All-Ireland for one league finalist.

Four of the five winners have also won an All-Ireland and the fifth, Mayo, who have been consistent qualifiers for the league play-off stages, are the only county to have disrupted the Armagh-Kerry-Tyrone grip on All-Ireland finals over the past four years.

In other words as Harte put it earlier this week: "People who dedicate themselves to the league can expect to be around in the championship."

So in the wider scheme, it will be interesting to see how the big three are holding up and which of the following pack make an impression.

Dublin ended 2005 as the boys most likely but the road gets steeper from here. Emerging talent in Cork and Galway makes them both works in progress whereas Mick O'Dwyer is on his last lap with a hitherto under-achieving Laois.

Of the elite group, Armagh are the ones who have been subject to most whispering.

In a way this is understandable, as Joe Kernan's team have been around for longest, winning an astonishing five Ulster titles (the first two under Brian Canavan and Brian McAlinden) in seven years. But time isn't standing still for players like Kieran McGeeney and Paul McGrane, players whose leadership qualities have been integral to the team.

Kernan points out that players establish themselves first before going on to assume leadership roles and cites Steven McDonnell as an example of a player whose performance levels had to rise before he became one of those galvanic figures who make things happen for the team almost regardless of his personal form.

Last year's league campaign facilitated under-21s Aaron Kernan, Ciarán McKeever and Brian Mallon in making the step up to senior last summer. How the holders further rejuvenate their playing stock will be followed with interest.

Kerry will feel the greatest pressure after the radical nature of last year's All-Ireland defeat. Refurbishing the team is one thing - Pádraig Reidy and Darren O'Sullivan indicate the sort of talent available - but restoring morale will be an equally important process.

Tyrone's modus operandi made them excellent candidates to retain the All-Ireland two years ago but the shock of Cormac McAnallen's passing turned the whole year upside down.

This season will be different and a true test of whether Harte has cracked the code on successfully defending the All-Ireland. Initial indicators will be on display in the weeks to come.