The 24-year-old Aucklander does not have to outmuscle his Mexican opponent or even prove he is fitter than the portly visitor when the pair fight for the vacant WBO world heavyweight title in Auckland this weekend.
All Parker has to do is jab, jab, jab and the belt could be his, national boxing selector Ryan Henry said.
"He does have a longer reach and he is a bit taller, so that is definitely in his favour," Henry said.
"Your jab is the can opener. If you start to land that jab, the rest of the punches are going to land."
"Kevin [Barry, Parker’s trainer] will be really wanting him to go out and just snap that jab. If you are firing the big hooks that’s when you can get caught by a quicker fighter."
For a blueprint, Parker, who has a professional record of 21-0, should watch how Lennox Lewis dismantled New Zealand boxing great David Tua when the pair fought for the WBC, IBF and IBO world heavyweight titles in 2000.
Lewis used his jab to keep Tua and his powerful left hook at a safe distance and won the fight by a unanimous decision.
Ruiz (1.88m) is a similar fighter to Tua in some ways. He is shorter than Parker (1.93m) and relies on devastating hand speed and power. He is also on the chunky side which can fool opponents.
"There are a lot of people commenting to me that he looks out of shape but you can’t underestimate him, and maybe it is the hand speed which has got him through."
While heavyweight bouts have the potential to be over quickly, Henry believes the contest will match the hype.
"I’m a big fan of Joseph’s and I really hopes he wins. He has already helped lift the profile of boxing and he hasn’t even won the world title.
"But I agree [with Parker’s camp], I do believe he is the underdog.
"I’ve done some research on Andy and he has had over 100 amateur fights and he is undefeated in 29 professional fights with 19 KOs.
"He is definitely more experienced but, in saying that, Parker has had a really colourful amateur career and was no mug either.
"It is going to be a good match-up."
While Ruiz is being billed as the fastest puncher in the heavyweight division, Parker boasts impressive hand speed as well. He is also a very good counter-puncher and well-equipped to deal with an opponent who likes to press forward.
However, Parker’s fight against Frenchman Carlos Takam earlier this year exposed some concerns.
He ran out of energy in the later rounds. He got hit more than he would have liked and his inability to finish off Takam suggested his power was not where it needed to be that night.
"That fight was perhaps one of the better learning curves for Parker in his career to get to this stage," Henry said.
"But Joseph has proven he can put you away with a hook or a straight right hand."
