Lee Holdsworth and Will Davison believeMarcos Ambrose believe is stepping back from his V8 Supercar too soon, having contested just two events in 2015 in his DJR Team Penske FG X Falcon.
Speaking on Inside Supercars, current drivers Holdsworth and Davison, along with expert commentator and five-time Champion Mark Skaife, expressed their surprise at today's news, which will see Scott Pye pilot the #17 in Ambrose's absence.
Ambrose was one of the standout performers at season opening Clipsal 500, making the ARMOR ALL Top 10 Shootout and keeping his Falcon clean at the treacherous street track. But his Grand Prix weekend was marred by incidents after qualifying towards the back of the grid.
In DJR Team Penske's statement released earlier today, Ambrose said it was his decision to step back from racing and while it stated he would drive for the Pirtek Enduro Cup, there was no further detail on when the two-time champ expected to be back behind the wheel full-time, despite sitting 12th in the Championship.
"I think he's come home ... can't believe how full on it is out there and, I don't know, I'm surprised," Erebus' Davison said on the Inside Supercars panel.
"I thought he did really well in Adelaide on the Sunday to make the shootout, I was pretty impressed, and the Grand Prix, once you qualified where you did, you were stuck there for the weekend anyway.
"He was probably frustrated, but too soon, I reckon."
For Holdsworth, who achieved an historic race win for Erebus this year and now races for Charlie Schwerkolt under the Walkinshaw banner, the competition is just too tight to give anything away these days.
"I think it's probably been a massive shock for him to come back and see where he's running," the Walkinshaw racer said.
"The last time he was in the sport he was dominating and running right up the front all the time, and if he did have a bad qualifying he'd be back up the front after the first couple of laps.
"[At the] Grand Prix he stuck it on pole his first time there - so to come back and probably not be as competitive at the grand prix as he was in his first round has probably thrown him out a bit and [he's thought], 'this is really hard'."
"You can't be giving anything away at the moment, you need that bond with your engineer, you need a great car, you need more than one car in a team, you need the data to get from that other car."
All three panelists agreed the progressive qualifying at the AGP didn't work in Ambrose's favour, and Davison suggested Ambrose's driving style may not be immediately suited to the new generation V8 Supercar.
"They're very different cars the way you have to drive them, the way you have to brake aggressively, get your lap time in that part of the corner I think is a bit different," the Erebus driver said and 2009 championship runner-up said.
"But he was going to get on top of it. The way he got in the shootout Sunday at Adelaide, I wasn't expecting him to be there. That just showed how good he is, I'm a bit blown away."
Holdsworth emphasised just how important qualifying has become in the Championship - drivers needed to be on top of the car early in the race meeting.
"It has become more about qualifying every weekend. Often the drivers are not making mistakes anymore ... and when you do qualify up the back, that's where you stay, if you do qualify up the front, generally that's where you'll stay," he said.
"So that's when you need to be right on top of the car. He needs to know that car 100 per cent. When he doesn't, obviously he's been here two minutes and hasn't got on top of it."
Skaife, who was a fierce rival of Ambrose during his period of dominance, emphasied how much pressure was on the Tasmanian.
"You don't just forget how to drive, lets not kid ourselves. He's one of the best drivers we've ever seen," Skaife said.
"The cars are difficult to drive and it's only a one car team based on getting information. I'm sure the guys would agree, if you have someone else beside you, it would be easier."