But the Blues boss reiterated he retains complete 'belief' in the trio of summer season-long signings who have yet to achieve the desired impact at PO4.
Forwards George Hirst and Gassan Ahadme, along with highly-rated midfielder Miguel Azeez, arrived on short-term deals from Premier League clubs Leicester, Norwich and Arsenal in the summer.
But none of the trio have managed to make a mark and become regular first-team starters under Cowley this term.
Norwich loan man Ahadme excelled in pre-season and has repeated that form in specially arranged friendlies - scoring 10 times in non-competitive fixtures for the club.
But he has failed to find the net for the Blues in a competitive fixture and has been restricted to just seven appearances in all competitions to date.
All eight of striker Hirst's League One outings have arrived as a substitute, with his two starts coming in EFL Trophy games against AFC Wimbledon and Sutton respectively. He’s still to get off the mark for his new side.
Meanwhile, Arsenal's teenage sensation Azeez has totalled just 59 minutes on the field in a Blues shirt.
The trio make up some of the loan quota of five players Pompey are permitted, with Manchester City goalkeeper Gavin Bazunu and Millwall's Mahlon Romeo completing the quintet.
Cowley admitted it could get to a situation where the Blues might explore alternative loan options by moving one of Hirst, Ahadme or Azeez back to their parent club in January.
However, he stressed the trio still have plenty of time to force their way into his first-team thinking.
Cowley said: ‘I think always (with) loans - the players come to you on loan because they’ve been starved of football at their parent club - the idea is for them to come and gain experience by playing regularly.
‘If that doesn’t happen then there’s always an opportunity for the two clubs to talk and look for the best way forward in the window, but we’re a long way away from that.
‘For us, I’ve been pleased with the attitude and work ethic of all three players and they need to continue to show that on a daily basis to force their way into the team.
‘I’ve got belief in them as players and as people. When you’re a young player, you have to be incredibly resilient and you have to keep fighting.’
Cowley revealed regular contact is ongoing between the Blues and all five of their loan players' parent clubs.
And he insisted Pompey will not be exploring any potential movement on the loan front until January draws a lot closer.
Cowley added: ‘We’re in regular dialogue with the players and we’re in regular dialogue with their clubs, so the lines of communication are always good.
‘Certainly, not until we get much closer to the window opening (will we evaluate the loans).’