Former captain Michael Vaughan was particularly scathing of Cook's performance following England's eight-wicket defeat to Australia in Melbourne, which left the tourists staring at a 4-0 deficit.
In an interview with the BBC, reported by the Mirror, he said:
He’s under huge pressure because his team are 4-0 down.
I hope he sticks with it, I hope he learns from a lot of mistakes that he made, particularly on the fourth day.
He got his tactics wrong on the third morning when (Nathan) Lyon and (Brad) Haddin came out. He just spread the field, England only needed one wicket and he just allowed momentum to go Australia’s way.
On the fourth morning, to take Stuart Broad off after the second over, to not bowl Monty Panesar, then to spread the field. You feel that he’s got a long way to go in terms of making sure that his tactics improve.
Cook scored 27 runs in 68 minutes during his first innings of the Melbourne Test and added 51 runs in 91 minutes during the second (stats courtesy of the BBC).
While those numbers aren't appalling, fans simply expect more from the experienced Cook both on and off the field. His batting average of 27.70 throughout the tour is subpar, and Cook's failings in this series have gone well beyond the numbers.
England put their faith in tall bowlers when the initial squad was picked, yet the likes of Boyd Rankin and Chris Tremlett have been used sparingly. While Mitchell Johnson's pace has been roughing up the English batsman, the hosts have been allowed to cruise.
And when the Australians pressured England, Cook couldn't come up with an adequate response. Counterpart Michael Clarke has used all sorts of mind games, including naming Cook's team before the Englishman had the chance to do so, and Cook has constantly failed to fight back.
As the Mirror article reports, Geoffrey Boycott, another former England player, was more inclined to share the blame when asked by the BBC:
It’s not just this one match because when you’re losing, everything is highlighted.
They’ve made a mess of everything.
In fact, they’ve got to the point where it doesn’t matter where any of them bat, they’re going to get out and they’re not going to win because they are shot.
Mentally, physically, they’re just down, their spirit is broken.
But it was the Telegraph's Andy Tilsley who delivered the biggest shot of the day.
Cook's performance may have jeopardised his long-term role as skipper, but he is still the only Englishman to ever score 25 Test centuries (and he's added 29 half-centuries for good measure). An overreaction at this stage would not be a step in the right direction.
Wicketkeeper Matt Prior expressed disappointment in a column he wrote for the Telegraph (via cricket365.com) after contributing only 107 runs in six innings during the first three matches, going as far as saying he felt like he had let Cook down:
The disappointing aspect for me is that I feel like I have let people down. In particular, I have let Alastair Cook down as captain and Graham Gooch as batting coach.
In a series like this you need senior players to stand up and make contributions. It is the least I expect from myself, but I have not been able to do it and for me that is the toughest thing of all.
Cook still appears to be well-liked and respected in the locker room, so clamouring for his tenure as captain to end would be very premature.
England will take on Australia in their fifth Test meeting on Friday.