Former fly-half Jonathan Davies has questioned Gareth Anscombe's retention ahead of James Hook in Wales' 2015 World Cup training squad.
Hook joined veteran scrum-half Mike Phillips and experienced hooker Richard Hibbard in being among the first eight players to be omitted.
Seven more will go when coach Warren Gatland finalises his squad on 31 August.
"I don't think Anscombe has proven enough at that level," said Davies.
Hook's versatility has counted against him according to former dual-code international Davies.
But the former Neath, Llanelli and Cardiff rugby union fly-half says 78-times capped Hook has also been guilty of "trying too hard" when given chances to impress in his favoured 10 jersey.
Davies wonders if Gloucester's Hook will have the "appetite" to continue battling to win Gatland's vote.
"It will be a call for James because he knows that he's maybe not what they want to play in that structural game," Davies told BBC Radio Wales sport.
The decision to add Phillips and Hibbard to those omitted amounted to "a bit of a shock" to Davies "because very rarely does Gatland make huge changes".
He added: "There's young scrum-halves coming up.
"Rhys Webb has taken his opportunity, Rhodri Williams [not a squad member], Lloyd Williams, Gareth Davies - there's enough strength there now.
"Are they looking for a sharper game away from that area because none of them has the physicality of Mike, but maybe they're a bit sharper than Mike around the base?"
And Davies felt Hibbard playing for Gloucester may have had an influence as Gatland pondered his hookers.
"Hibbard… he's gone to Gloucester, Scott Baldwin's done well, Ken Owens is back [from injury] so I suppose it's just a preference call for them."
Former Wales centre Tom Shanklin believes Gatland should have held on to the British and Irish Lions trio, whose combined total caps is 218.
Shanklin said: "They all offer a lot to the squad. You look at the experience that Mike Phillips brings, it way outweighs the other scrum-halves that are there.
"James Hook's utility could benefit the squad, he can play centre, ten or 15.
"And you look at Richard Hibbard and the physical edge that he brings.
"[These are] three big calls by Warren Gatland. We know he's not afraid of big calls but it took me by surprise."
Ex-Wales hooker Mefin Davies - like Shanklin, a 2005 Grand Slam winner - says after the initial shock over Hibbard, came a less worried realisation over that position.
"After reflecting on the reaction you've just got to realise, really, that Ken Owens and Scott Baldwin are still in the camp and they are very good hookers and have done well for Wales.
"Kristian Dacey is there as a youngster, very inexperienced, but he played a lot for Cardiff Blues last season."