Jackman utilised his playing resources as Dragons lost 42-10 to Saints in pre-season at Rodney Parade.
He admitted there were several positives to take from the outing in the first half with Rhodri Williams grabbing a deserved try.
But with the new Guinness PRO14 season fast approaching, Jackman is ready to start picking his best side when the team travel to Kingsholm to face Gloucester Rugby next Thursday.
“We have given everybody lots of game time in pre-season, which is good, and the pecking order is starting to sort itself out,” admitted Jackman.
“From now on we are going to pick or best team. Players are going to have to prove the right to play and we will have settled combinations.
“There were elements of the performance we really liked, the first half particularly,” he added. “I just felt when they brought on changes and we made changes too and became loose and disjointed. We lacked cohesion.
“I was very happy with the first group in the first half. Against the wind, Rhodri Williams put us in the right areas and we got a good try.
“We are disappointed with the two intercepts and lack of cohesion, but that is what pre-season is about and we have got quite a few bodies to come in now over the next two weeks.”
Jackman was delighted to Tyler Morgan and Dafydd Howells back in action and revealed the likes of Corey Hill and Elliot Dee could now feature at Gloucester.
“A big positive was Tyler coming back and playing 20 minutes – that is huge for us,” he said.
“Dafydd Howells has also got 20 minutes and we want to nurse those guys back so they are viable options for round one.
“We will get Leon Brown, Elliot Dee, Corey Hill, Hallam Amos back involved this week and Ollie Griffiths will potentially be around for Benetton. Suddenly your team looks a lot different with more experience, power and talent.
“We’ve had a good pre-season so far and we are not going to let a poor 40-minutes impact on that. Northampton showed power up front and put a squeeze on us, but we will fix that.”
