Boucher backs Bairstow to succeed
Bairstow has, by some estimations, been unable to take seven of the 23 opportunities (until the end of South Africa's first innings in Centurion) that have come his way as wicketkeeper in the four Tests. While a couple of the chances he has missed - not least a stumping opportunity in Durban - have been fiendishly difficult, several have been relatively straightforward by international standards.
In the current match, he missed opportunities against all three centurions - Stephen Cook, Hashim Amla and Quinton de Kock - and there were times when his team-mates were unable to hide their frustration.
But Boucher, the most prolific wicketkeeper in Test history, believes Bairstow has "a big future" at the top level and has urged the England selectors not to "mess around with his head" by dropping him now.
While much the same could have been said about Jos Buttler - dropped for Bairstow after his form with the bat fell away - Boucher revealed that he and Bairstow had recently discussed the challenges of the role after Bairstow requested a meeting.
"He just wanted to have a chat with me, I think it was after I did a stint on TV explaining the mental aspects he might be going through and a couple of small technical things that could help him out," Boucher told Press Association Sport.
"For a youngster to speak to a guy who's been in the opposition side was fantastic to see and I used to do the same with people like Ian Healy. He's very keen to learn about his trade.
"It was a very relaxed chat. I just wanted to find out where his head was at and basically told him I'd been through some of the same sorts of things, that he's not the only one who's gone through it and he's not alone."
As Boucher sees it, Bairstow's problems are not so much technical as mental. While he accepted there are some technical adjustments Bairstow can make, Boucher feels that more significant progress can be made with a more resilient attitude and an ability to put any mistakes behind him, so they are not clouding his mind when the next opportunity comes along. He also made the point that Bairstow's batting - which in this series has seen him score more runs than any England player other than Joe Root or Ben Stokes - is highly valuable.
"I think there's a big future for him at this level but he has to be as mentally tough as possible in the face of criticism," said Boucher. "I don't think he needs big technical changes, they are all pretty small. It's more the mental aspect of getting over one or two dropped catches as quick as he can and not letting them affect the next one.
"The step up to test keeping is quite big and he needs to close that gap but his attitude is good enough for him to do it.
"Is he worth having in this England side? Absolutely. You don't want to mess around with his head and drop him now. That's a dangerous move to make because it risks showing a lack of confidence in a youngster's game.
"There is some room for improvement there. He's not a natural keeper but he's proved he has the goods with the bat and there is more than enough talent there for him to become a very, very good allrounder for England."
George Dobell is a senior correspondent at ESPNcricinfo