Matt Clarke believes having the flexibility to switch formations gives Pompey an extra string to their bow.
Kenny Jackett has mainly used a 4-2-3-1 system this campaign, similar to the one former manager Paul Cook deployed.
However, the Blues boss has also rolled out wing-backs on several occasions.
He last played three central defenders in Pompey’s defeat to Gillingham.
Although the Blues fell to a 3-1 loss, the wing-back system looked a well-oiled machine in the first half as Jackett’s side went into the break with a lead.
Despite the formation being shelved since then, Clarke would have no qualms playing it again.
He believes having the ability to adapt during games gives Pompey an added dynamic.
The centre-back said: ‘I’ve played in a back three only a handful of times.
‘It’s something the old gaffer tried once and this gaffer has tried a few times.
‘It’s something we have tested and flirted with but have never really committed to in a block of games and something we maybe need to commit to in the future.
‘For me, it’s not all that different. Everyone who has seen me play can see I like to wander forward as it is!
‘It definitely gives you a different dynamic as a side.
‘There are differences and it’s something you need to work on. If it is something we will use more often going forward, then I’m sure more work on it will be done to make sure it is right.
‘You’ve always got to have a plan B or a back-up plan.
‘Sometimes you’ve got to hold your hands up and admit what you’re doing isn’t working and have to change it up. If it’s something that will give us an advantage or get us a foothold in a game then it is something we will need to use.
‘Against Gillingham, the first half was one of the better first-half performances we’ve had this season.
‘It looked liked it was going to be a good day but the second half didn’t go how we wanted it.
‘It’s whatever is best on the day.
‘If teams set up very narrow then you maybe need to have wing-backs and we need three central defenders.’
After the Gills loss, Jackett reverted to a back four and dropped Christian Burgess to the bench.
In the 2-0 win at Oldham, all four Pompey defenders were aged 21, while the average only increased by nine months against Oxford as Dion Donohue replaced Brandon Haunstrup.
Clarke shrugged off the suggestion the Blues’ rearguard is lacking a senior head.
‘We know what good players are here,’ he said.
‘Everyone is first to say when things don’t go right that we need some experience.
‘They say they’re all too young and you can’t have that many kids at the back.
‘That’s not something we want.
‘We want everyone to say what a good bunch of youngsters they are, they can bring the club forwards.
‘As young players, we want to go out there and prove we are good enough and can play at this level.
‘It doesn’t matter what the average age of the side is.
‘If we’re good enough, we will play and hopefully win games for the club.’