Tomorrow, Tommy Griffin wears number three. In recent seasons he has worn numbers six, eight and nine, and 11, and also some other less significant numbers between one and 15. He is Gaelic football's ultimate utility man. He is fast onto the ball and courageous in fighting for it. He's also actually a decent user of the ball. And if you are waiting for me to finish up this little overview of Tommy Griffin by landing a giant criticism at his feet, then you are going to be disappointed. This man would be welcomed onto any football team in Ireland.

However, Tommy Griffin is not the greatest Gaelic footballer in the world and neither is he the greatest Gaelic footballer in Kerry. Tommy would struggle to make it inside the top 10 greatest footballers in Kerry.

Whether Tommy Griffin would be able to bolt down a place for himself on the Dublin or Tyrone or Cork teams at full-back, centre-back, the middle of the field, or centre-forward is extremely doubtful. I think not. In fact, in my opinion, not a chance. He might be in with a shot at a central position on the Meath team but he'd hardly make it up the centre of the Mayo team. Donegal? Maybe. Kildare? No.

There we have it.

The troubled state of Kerry football over the last 18 months or so is probably best illustrated by the fairly urgent and repeated appearances of Tommy Griffin in so many key positions on the field. Normally the utility man is asked to fill in occasionally in one of the big positions on the field and after that he's to be found moseying around on the bench, or holding onto for dear life a wing-back or a wing-forward role for a season or two.

But not Tommy Griffin. Not at this desperate time and place in the history of the greatest football team in the country. Yep, Tommy is wearing number three alright as we await the latest battle between Kerry and their most formidable, illustrious opponent of them all. We hope for an epic. We might be lucky. We don't know. For sure, we will see two teams on the field for tomorrow's quarter-final who will both share an uncertainty about the merits and abilities of the men – in blue, and in green and gold – who will be filling the full-back role and the midfield positions.

If Kerry are taking a chance on Tommy Griffin doing the job for them at number three, then Dublin are still looking for Denis Bastick in his first season to deliver the one all-powerful, mean-spirited, calming performance which would allow Pat Gilroy and everyone on and off the Dublin team to take one giant deep, relieving breath.

If Kerry are dicing with Father Time by asking Darragh Ó Sé to dominate in the middle of the field for two more months and, if they still feel utterly dependent upon the limited skills and ball-winning ability of Seamus Scanlon as Darragh's best support, then Dublin are still waiting to find out for sure who should be making up their starting midfield partnership. The championship has already sped past its halfway point and Kerry and Dublin – the most tantalising pairing there is in Gaelic football – don't know for sure about their numbers three, eight or nine. Jack O'Connor and Pat Gilroy know no more than the rest of us which is interesting in itself, is it not?

Ploughing into any firm prediction about the outcome of this game is also not helped when we consider that neither of the two men who will be wearing the number six jerseys are first choice, and one of them was not even second or third choice at the beginning of this summer.

Mike McCarthy's about-turn after his lengthy enough period in retirement from inter-county football is a double-headed coin: as relieving as it is worrying for Kerry supporters. He is a wholesome and brilliant defender, and it's not like he has spent the last couple of years at the dinner table, or driving younger men and kids to games. Remarkably, McCarthy looks like he only turned his back on the Kerry team for a couple of weeks.

It might look like he was never away at all and it may be very good to have him back but psychologically every defender in the Kerry dressing room knows that either they were unable to make the centre-back position their own at this oh so precarious time in the county's history, or else they were deemed by the team management not capable of doing so. McCarthy will fill the role more than adequately alright, but this has been a very bad, demoralising month for the Kerry defence and for everybody living in the same room as that defence.

Advantage Dublin?

Almost. But not quite. If I had a choice between Ger Brennan and Bryan Cullen for centre-back tomorrow afternoon, I'd still go with the St Vincent's man, Brennan. I'd bet that Pat Gilroy and Mickey Whelan would also choose their own clubman for this particular game.

Brennan has been too quick with his fists on a number of occasions this summer and he was, quite correctly, tossed out of the Leinster final for one such Ricky Hatton impression. Consequently, Bryan Cullen grabbed the chance he has been waiting for over the previous six-and-a-half months and was outstanding in his tackling in the second half of the Leinster final victory over Kildare. And also in his controlling of the game. Cullen is still a young man and, as we saw, he remains an outstanding athlete and a very smart footballer. But unfortunately he is also strongly identified with the Dublin team of the last half a dozen seasons that was wholly incapable of grabbing games at this most blood-curdling part of the year and ruthlessly killing them off.

Brennan on the other hand, as a Vincent's man, comes from old-style, more ruthless, win-at-all-costs football stock. He has been aggressive on the ball and overly-aggressive off the ball, and his style and panache was exactly what this Dublin team needed this season. He is not the complete footballer or athlete, as Cullen is, but Brennan had 'All Ireland winner in a first season' written all over him in my opinion. His loss is incalculable. And if Dublin do win this quarter-final, Cullen or no Cullen, Ger Brennan will be back!

Tomorrow, indeed, will be a day for good defence. And may the best defence win. Dublin look that little bit sturdier, happier even as a unit, and while Brennan's absence will be felt, this is an occasion which may be just right for Denis Bastick to repay the faith which has been shown in him since the beginning of the year. Shutting Tommy Walsh down will bring Dublin right to the very edge of victory.

Bastick was also chosen by Gilroy and Whelan as much for his desire and passion, and his doggedness and his willingness to give a dig if needed. He's also a strong footballer. But more than anything else, Bastick is a step back in time to when most of the gentlemen on a Dublin full-back line were fully respected and rightly feared.

In other words, Denis Bastick is there to discourage and encourage, and ultimately to lead Dubin to victory. Same as it once was. And if Bastick leads, Dublin can definitely win.

• • •

Last Sunday, I ended up in a wee bit of a schemozzle with this newspaper's Gaelic games editor on this same page. Actually, it was not really a schemozzle. Kieran Shannon, a man whom I like and admire as a writer, and of whom I still think kindly, came up behind me and gave me a couple of slaps across the back of the head about a few things I had said about Colm Cooper, Peter Canavan, Colm O'Rourke and outstanding forwards we have all known.

I didn't get to retaliate then. And I'm not seeking to do so now. Anyhow, tomorrow's huge and hopefully great showdown between Kerry and Dublin will in my opinion have less to do with forwards and more to do with defenders.

However, in seeking to underline that Colm Cooper has done more before the age of 25 than Canavan and O'Rourke combined, Kieran Shannon did lay down an incorrect statement, which went like this: "The country had never heard of Colm O'Rourke before he hit a 14-yard free off the upright against Dublin in the 1983 Leinster semi-final. O'Rourke was then 25. Cooper was only 25 last year."

As it happened, as Kerry and Dublin were starting to wage perhaps the greatest duel in GAA history, it was Colm O'Rourke who at 18 years of age, stepped between them and almost kept them apart for good. In his first Leinster final, in 1976, he scored one goal and two points against Dublin and crucially hit a penalty wide in the second half. Colm O'Rourke, single-handedly, had the greatest say in the Kerry-Dublin era – happening or not happening – and all of the country knew of him.

After that, O'Rourke's career went into a tailspin for two years when he broke his leg and severed his knee ligaments in a cruel fashion back in the darkest of days when such an injury was deemed the end of a football career. Colm O'Rourke did not fully restart his career until 1983.

But, as I've said, tomorrow is a day for defenders to be counted first, forwards afterwards. When the game does come down to the courage of one or two men to make the most of their scoring chances, nobody should doubt Colm Cooper. I may be one of his fiercest critics, but if so my criticism is forged out of respect and amazement at his repertoire of skills. This is an occasion tailor-made for geniuses. Cooper, even if he is under-performing, is the only fully-fledged genius on the field. If he does not manifest himself in magnificence for a life-or-death game against Dublin, then his confidence and appetite for the game may be lost for good. That would be a shame for all of us. His career accomplishments would then lie far short of O'Rourke or Canavan, but let's not think about that.

The forward on the field with the greatest pressure on his shoulders at the beginning of the game is not actually Colm Cooper, but Bernard Brogan. He has been the all-round most spectacular forward in the country so far this summer. In the Leinster final in particular, each of his points had double their face value as each sickened Kildare and tore at their self-belief.

The younger of the two Brogans has indeed built higher standards for himself than any Dublin forward of the last decade. We are seeing Colm Cooper or, more particularly, Stephen O'Neill-like finishing from him, but can he keep scoring? Ger Brennan and Bernard Brogan have been the essential difference for Dublin this year. With Brennan gone, Brogan simply has to deliver.