The composed midfielder signed for the Shrimpers from Swindon Town last month.
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And Joe Acklam - who reports on the Robins for the Swindon Advertiser - believes Oldaker could prove to be a shrewd piece of business of Blues.
"At National League level, in a top team with a defined system, I can see him looking like one of the best players in the division because his technical ability is miles above the standard," said Acklam.
"I can remember Ian Holloway saying that he was one of the most gifted players he had worked with when we signed him last summer.
"In the right situation, I could see him playing in League One, so I would be very excited about it as a Southend fan, so long as the right plan is there for him.
"If Kieron Dyer knows how he fits with everyone else, then he is the sort of player who can get you promoted."
Oldaker made 45 appearances for Swindon last season, including 39 games in League Two.
But it ended up being a mixed campaign for the 27-year-old.
"Oldaker's time at Swindon was fairly complex, sort of like a sparkler that slowly fizzles out," said Acklam.
"Early in the season, his eye for a pass and maverick nature to try flicks and tricks made him so exciting to watch but in the back half of the season, he was rarely impacting games.
"It does need to be pointed out that Swindon went from being a very coherent and exciting team in the first half of the season to one that did not have a clear identity and players have admitted that things were changing frequently and they were not sure what was going on.
"Oldaker seems to have been a victim of this."
But there were other reasons behind the inconsistent form.
"Oldaker's relationship with Finley Munroe was a big part of how Town played up until January, before he got recalled by Aston Villa and sold to Middlesbrough," said Acklam.
"The pair were really close on and off the field, and Oldaker was never right without him but I was a big fan of Oldaker's.
"I really enjoyed the audacity he played with when things were going well but when things got tough, it would be fair to say that he didn't step up.
"Many fans were less happy with him and he got booed after a particularly ineffective performance at Shrewsbury Town in February.
"He reacted to that and it is that incident that essentially meant he was always going to be sold this summer."
But there were still positive moments for Oldaker.
"His main strength is how comfortable he is on the ball," said Acklam.
"If you want to see a great example of his play, then find Swindon's third goal against Crewe Alexandra last August and you can see the sort of passing he is capable of.
"His best football for Swindon came as a more advanced midfielder, but he has played most of his career as a deep-lying playmaker, and he is so calm and free on the ball when he feels confident.
"He loves a backheel and an outside of the boot pass, so when he feels comfortable in a system, he will look like a top player.
"He also has great set piece delivery and can score from free kicks. "
But what about any possible weaknesses?
"His biggest drawback is that he is not the most athletic player," said Acklam.
"He will try to press and do his bit defensively, but he is not going to be haring around and snapping into tackles to get the ball back.
"Sometimes that can come off like he is not trying hard and I don't think that is fair.
"He will put the effort in but it is just a case of him not being an especially physical player."
Prior to his season with Swindon, Oldaker made 113 appearances during a three year spell with Chesterfield.
And the 27-year-old is still highly thought of by Spireites supporters, including Alex Ambler.
"DJ was well liked at Chesterfield earning the tagline ‘different gravy’," said Ambler.
"His way of dictating play in the middle of the park had you lauding his quality.
"The only gripe came towards the end of his time with the club when his calm became too calm and more times occurred where he was maybe caught in possession and, on occasion, played a loose pass or two.
"But DJ is a very cool and calm centre mid who can make the game look effortless at times.
"He will never be rushed on the ball and will aim to keep possession ticking.
"Oh and he’s got a pretty sweet free kick in his locker too."
Oldaker will now aiming to show that for the Shrimpers in a style which could be quite familiar for the midfielder.
"Kieron Dyer has been under tutelage of Paul Cook for many years and so in turn will likely look to instil a similar playstyle at Southend," said Ambler.
"Darren would be key to this possession-based style of play and I would imagine he would be a focal point in building out from the back.