All-Ireland SFC Semi-final Dublin v Mayo: Despite their impressive progress to date Seán Moran looks at why some niggling doubts persist for Dublin.

Last August Dessie Farrell's injury-time goal against Tyrone did little but take the double-digit look off Dublin's quarter-final replay defeat. The winners were on the way to an All-Ireland and no one was entirely sure where Dublin were heading. The best of the rest maybe but how great was the room for improvement and how speedy its likely attainment?

This weekend some of the questions have been answered and others haven't. This has certainly been a year of consolidation for Dublin: the first team to retain the Leinster title since the county's previous All-Ireland season 11 years ago; the first side from the province to win an All-Ireland quarter-final at the first time of asking. But. But. But.

Tomorrow's Bank of Ireland All-Ireland football semi-final against Mayo is widely regarded as Dublin's first match with serious opposition this championship.

Longford's young side nearly beat them back in June and whereas the consequent changes to the team have worked well, to what extent have they been tested in matches won by an average of over 10 points?

The reservations centre on three areas: progress so far has been based on unfeasible percentages of possession at centrefield; the forwards have required a wealth of opportunities for what they have scored and the full-back line, coping with starved forwards and protected by the phenomenal form of Bryan Cullen at centre back, hasn't been put under real pressure.

Martin Carney, an analyst with RTÉ's Sunday Game and an experienced mentor in Mayo football, has watched Dublin over the past couple of years and whereas he shares the ambivalence he also believes there are positive signs for the Leinster champions.

"I think we'll wait and see but the power and organisation has impressed me. There's a greater physicality and aggression to their play. They have learned from the Tyrone defeat. But how good the standard in Leinster was remains to be seen. I'm not yet convinced. They need to play a team like Mayo - not that I'm saying Mayo are a benchmark but they're a step-up from Dublin's other opponents.

"The organisation has been noticeable in the kick-outs and the defence. Bryan Cullen's switch has been important, not just for his own performance but the way he brings out the best in others."

Cullen's relocation has been one of the pivotal changes but the only surprise is it took so long. Dublin manager Paul Caffrey and his selectors had used Cullen at centre back in last year's National Football League but by the time the championship came around, moved him back to wing forward where his ability to win breaking ball and scoring capacity of a couple of points per match was felt to be needed.

Earlier this year he continued in that role with Coman Goggins at number six but Cullen had a storming campaign at centre back as DCU won the Sigerson Cup, leaving the question open.

DUBLIN'S ACID TEST came early in the championship. In the tight confines of Pearse Park, Longford, the home team gave Caffrey's first team a thorough examination, which threw up alarming results.

"Having watched Dublin in the league," says Longford manager Luke Dempsey, "we got it right tactically by targeting Stephen Cluxton's kick-outs and using Paul Barden's pace against Coman Goggins, who was playing centre back. We also knew Niall O'Shea (at corner back) was inexperienced.

"They got a fright but we should have won and maybe would have if David Barden had showed more composure in front of goal."

O'Shea made way for Cullen's move back to defence with Paul Griffin dropping back to the corner. The new full-back configuration has had its troubles for a period in the Leinster final when Offaly's twin threat of Niall McNamee and Thomas Deehan exerted early pressure but overall it has played well.

The surprising feature of the centrefield domination is the basic moves have been on show all year.

Ciarán Whelan is having his most consistently effective championship campaign but the performances of his partner Shane Ryan have been unexpectedly productive.

Ryan has played a free role, moving wide to collect Stephen Cluxton's precisely placed kick-outs. Strangely, apart from Longford, none of the other opponents have had any great success tracking Ryan and anticipating Cluxton.

Dempsey admires the way Dublin's backroom team crunched the numbers after the near-miss in Longford and the determination of the players to intensify their efforts.

"Their management is very professional. After each match their analysis is very good and they have improved radically since June.

"I'd pick out the improvement in Shane Ryan. Some players can almost take refuge in setbacks. He was taken off against us and could be categorised as an average enough player. But after the Longford game he could have disappeared into that zone of feeling sorry for himself but he knuckled down and came back greatly improved."

TOMORROW DUBLIN'S CENTREFIELD is up against the most formidable unit it has faced so far in Ronan McGarrity and Pat Harte. If the failure to do adequate homework came against previous opponents, that's unlikely to be a failing of Mayo's management team of Mickey Moran and John Morrison.

According to Carney, Dublin's ability to react to the challenge of a centrefield that has also become used to getting its own way will be critical.

"There are two guys capable of marking them and that could cause trouble, I wouldn't be surprised to see Darren Magee coming into the match sooner rather than later. Mayo will be better switched on to dealing with that tactic (Cluxton's kicks to Ryan). How will Dublin cope if that happens? Something has to give."

Laois have been Dublin's main rivals in Leinster over the past two years. Having been toppled in 2005 by a last-minute free, there were expectations that Mick O'Dwyer's team would exact revenge in last June's provincial semi-final.

Instead they were blown away but the collapse followed the departure of injured centrefielder Pádraig Clancy, up to which point the match had been evenly contested.

LAOIS SELECTOR Declan O'Loughlin is reluctant to read too much into the misfortune. "Clancy was playing well and it would have probably been a tighter match if he hadn't had to go off but the result would have been the same."

If there is ambivalence triggered by doubts about the team's opponents to date there is an acceptance that physically and mentally, Dublin are stronger and more aggressive.

The link-up with Dr Niall Moyna at DCU has resulted in a regime of conditioning that has made the team more forceful in the tackle and more dynamic on the ball.

O'Loughlin has no doubts that Dublin have improved over the past 12 months. He also sees an added psychological edge to their attitude.

"They're certainly a better team. They were more effective than last year, more "in your face" like Tyrone - and I don't mean that in a negative way. They would have seen that as the direction they had to develop to match the Ulster teams There's also great understanding and teamwork. As a management team they've also improved."

Dempsey knows many of the Dublin players from his spell managing Leinster in the Railway Cup. He was impressed by their attitude. "With Leinster I couldn't get over how committed they were. People in the country think they would have a more intense commitment to the jersey than a typical Dublin player but I doubt it."

The country at large can judge for itself this weekend and maybe in the month ahead.