Pietersen admitted to feeling frustrated at England's inability to capitalise on periods of competitive play during the first two Tests and expressed a belief that they could be subjected to another 5-0 series defeat, despite his view that there was little to separate the two sides.
"There are signs with the way that the guys capitulated on the last day of the last two Test matches that, unless they really start well in Perth, then it could happen," Pietersen said. "But this Australian side isn't as good as some of the Australian sides England have played in Australia.
"I think it's a damn shame that the toss was not decided in a different way in Adelaide and that the bowlers didn't bowl better in the first innings in Adelaide and also that there wasn't just a general all-round better performance at the Gabba, because I don't think that the bridge between the two teams is what the results are reflecting: the ten-wicket loss and the 120-run loss.
"I don't think both teams are actually that unevenly matched. I think there are inexperienced players in both teams."
Pietersen, whose international career ended in the wake of the last Ashes whitewash in Australia, was scathing in his assessment of the batting line-ups of both sides. Only two players, Steven Smith and Shaun Marsh, have scored a century so far in the series.
"England are very nervous when they go out to bat and it's frustrating because I want to see somebody try to get on top of the Australian bowlers"Kevin Pietersen
"I just think the batting from both sides is no good," Pietersen said. "I don't think it's any good at all. I think there's insecurities with [Cameron] Bancroft, [Usman] Khawaja, Marsh's set up, [David] Warner hasn't made a play yet in the series apart from that red-inker at the Gabba.
"And then for England, Cook is all over the place, [Mark] Stoneman's shown signs but not converted, [James] Vince is very unconvincing, [Dawid] Malan is very unconvincing and [Joe] Root can't convert a fifty.
"So that's my issue, the batting sides are not very good and the unit's not very good at all. There's a lot of inexperience and the experience has also - apart from Steve Smith's hundred, being the experienced player - none of them are performing either.
"So that's why I actually think the difference in the teams is not that big and that if England actually did turn up properly for four or five days of a Test match, which only they can do, then they can get a win."
Pietersen also questioned Cook's body language and his desire to keep batting at the highest level. Cook has posted scores of 2, 7, 37 and 16 so far in the series and, while he looked more comfortable in Adelaide, his early dismissals have added to the pressure on the captain, Root, to form the backbone of an England batting line up that has crumbled at key times during the first two Tests.
"It looks like Cook is not very interested," Pietersen said. "Just the way that he's got out, the manner of his dismissals and also the way he's walked off the field once he's got out. That's the sign of a bloke who goes, 'You know what? Maybe my time is up.' But he's also quite resilient so can he turn it around?
"He's a wonderful player and has been for England for a hell of a long time. This will be his 150th Test match, so you never know. He might be able to put up a performance in his 150th Test match, which gives them a lot of energy and excitement going into the WACA. He's got a Test hundred at the WACA before. But who knows? That fire burns in your belly for a number of years and then eventually it starts to go out. I had spotted it before the series and there's certainly no signs at the moment to prove there's any fire in Cook's belly."
Cook isn't the only batsman to draw criticism from Pietersen, who took apart the technique and mental application of virtually every specialist batsman in both sides, highlighting the tendency of players to hang deep and play off the back foot.
"Shaun Marsh is the only one in the batting order who really gets a proper big stride in and plays off the front foot," Pietersen said. "Cook plays inside his crease, Stoneman - he gets in a good position - Vince actually gets a nice stride in and has showed signs but I don't know whether he's mentally strong enough. Root plays back, Malan's back in his crease.
"The Australians, you've got Bancroft who comes at it, Warner's a back-foot player and doesn't really punch down the ground, Khawaja's a back-foot player, Smith is what Smith is and he manages his technique, [Peter] Handscomb - he plays French cricket."
He suggested that England's batsmen, in particular, were far too tentative and appeared "very nervous" against the three-man pace attack of Mitchell Starc, Pat Cummins and Josh Hazlewood.
"For us we can't understand how there's just no oomph, there's no drive, there's no real determination to say, 'Well, these Australian bowlers are not bowling 100 miles an hour'," he said.
"They're not bowling at a speed they haven't faced throughout their careers. One or two balls have been 150kph but they're in the 140s, which isn't something that people haven't faced before. So to me it looks like the England batters are making out that this Australian bowling attack in their head is some of the fastest they've ever faced, is the scariest bowling they've ever faced and it looks like they're just very nervous when they go out to bat and it's frustrating as a commentator because I want to see somebody try to get on top of the Australian bowlers.
"That's what I did in my career. I was like, 'No, no. The quicker you come the quicker you're gonna go.' And even if I didn't feel good on occasions, I made it look like I felt good because that's the way you need to do what you need to do in Australia. You need to get on top of them and you need to show them that you're not scared and you're not worried and there's no one in that England side at the moment that doesn't look scared.
"It takes guts, it takes determination, it takes bravery and it takes a backing of your skill and it takes positivity."