"The longer a year goes on, it gets harder," O'Neill explained of the process. "Teams are getting hungrier and hungrier to beat you and they're preparing for you because they know the type of game you play and know you inside out. That was probably the hardest thing we found."
To contextualise O'Neill's comments, in two Sundays' time, Tyrone will meet the latest team to try and repeat Kerry's 2006/'07 trick of winning All-Ireland SFC titles in successive years, Donegal.
Not just that, Jim McGuinness' men will have the opportunity to extend their Championship hex over Tyrone into a third consecutive win, kick-starting their bid for an Ulster title three-peat.
"It'll be a lot more defensive probably and not as open or free scoring so we'll just have to take the good from the Dublin game and be prepared for a different challenge on Sunday week," O'Neill says.
And as it happens, Tyrone – after a fine League campaign – are unanimously considered the most likely contenders to prevent that particular run continuing.
"You have to announce yourself this year and we're hoping to do it this year," O'Neill insists. "Time will tell; we've a lot of new boys in and they gained a lot of good experience from playing in Dublin in a Division One final. Hopefully they'll learn from that and be able to close a game out when one or two points ahead because I'm sure it'll be very close as well. We just need to use that experience to get over the finish line this time."
O'Neill missed the one-point League final defeat to Dublin, falling to a freak injury sustained in the warm up to the match after tripping over two undetected footballs, a blow he ranks now as the most bizarre of his career.
"It was just unfortunate," he recalls. "I stepped back and there were a couple of balls behind me and I went over on it. I was getting a wee bit of bother from the ankle anyway so I didn't want to take the chance on it."
He is back fully fit, as is team-mate Peter Harte. And given his exploits in the League, Tyrone are all the better for his well-being.
"Some of the new boys who have come in have brought a new vigour to it, a new energy around training," he says, spreading the praise thinly.
"Unfortunately, we've found ourselves wanting in the past couple of years and we were disappointed and hopefully we can avoid that this year.
"We got a few lessons along the way and performed well in some games so we're hopefully on the right road," O'Neill adds.