The Jack factor is a major concern to Wexford Senior hurling manager Davy Fitzgerald, just as he was about to emerge as an important figure in the county's Allianz National League Division 1A campaign.
Guiney, the Rathnure talisman, had emerged from the substitutes' bench in their opening two league games against Waterford and Cork, contributing an important role in his time on the pitch.
However, his enforced withdrawal from the squad for their first defeat of the year, the league crunch tie against Tipperary in Semple Stadium on Saturday evening, cast a shadow over proceedings.
The Wexford manager has revealed that the big attacker is suffering from a cartilage knee injury that could yet rule him out of the remainder of the league campaign, all of which is reliant on medical prognosis over the next 24 hours.
Guiney has been carrying the dreaded knee problem for some weeks but it has finally caught up with him, forcing him to miss the Tipperary game, while an operation at this stage would rule him out for up to six weeks. Now every avenue is being explored to ensure the attacker is back in action sooner rather than later.
There's no doubt that Jack was about to emerge and fulfil his full potential as an inter-county hurler, having come through the Davy training programme which had brought him to a new level of fitness.
While this injury may be a setback, let's hope it's short term, as the attacker has a key role to play in the side this year, particularly in the championship round-robin series. No doubt the backroom team are aiming to have him back at one hundred per cent for the crucial games that lie ahead.
Jack was really looking forward to the remaining games in the league. Ironically, speaking at the launch of the new Sports Physio Ireland Clinic, he spoke of having made the right call at the right time when he headed off travelling in 2016. He got a buzz out of it and was back for year one of life under Davy Fitzgerald in Wexford.
If he had waited another year to tackle the travelling bug, he'd have missed out on the way the county rowed in behind the team, particularly that thrilling night when they took out Kilkenny last summer.
'You are watching Wexford playing and, when they are doing well,you do kick yourself, and even when they are doing bad you are kind of kicking yourself as well,' Guiney said.
'Yet you don't want to miss out on the travel, you'd probably wake up when you are 40 and if you don't do it you'll look back and you'd say, why didn't I?'
Guiney, in that interview, felt that there is a shift in the Wexford mentality now. 'You can say that there is belief and you are going to win this, that and the other, but until you start winning a few games, it doesn't really sink in.
'I think there is a bit of belief there, we're all very aware that it's still February, teams are really only getting going. But as a group, we're pretty happy as to where we are even though it's early days.'
Following three league games there is no doubt that Wexford are as serious a panel as any county. Back in Division 1A, they have produced two victories, taking the scalp of last year's All-Ireland runners-up, Waterford, along with reigning Munster champions, Cork.
While one would always be concerned at a loss, Saturday's battling qualities, which came ever so close to producing a draw at the end of a tremendous rally, served notice that this is a side prepared to fight.
In that second 35 minutes Wexford created five goal chances, the only blemish being that they failed to convert, but the fact they are now threatening in that department is something that will not be lost on Clare for their visit to Innovate Wexford Park on Sunday.
Mistakes have been a problem for Wexford in this pressure zone. Should they limit their errors, become more composed in their play, and build the confidence to deal with the ball whether on the ground or in the air, they will become a serious force.
The Tipperary game served to highlight that mistakes will be punished at this level. Tipperary's goals resulted from defensive errors, but one felt that Aidan Nolan, whose hurley was held, should have had a free out in the lead up to 'Bonner' Maher's additional time goal.
Should Wexford maintain this level of performance and commitment they are ready for a place in the league knockout stages. We are looking forward to the return of Clare who will no doubt not fear the Davy revolution, having had a similar experience of their own.