Former England batsman Geoffrey Boycott believes Graeme Swann's decision to retire in the middle of the Ashes is "honest" and "brave".
The off-spinner has called time on his career with the tourists 3-0 down in the series and having already surrendered the urn.
The 34-year-old has come in for criticism on social media sites for the timing of his decision, with Derek Pringle, who took 70 Test wickets for England, saying on Twitter he "should have seen the tour out as a senior player" unless he was injured.
But Boycott told BBC Radio Five Live: "He hasn't been right the whole series, he hasn't been the Graeme Swann we know. It's very difficult to get up for top-class sport when you're not bowling your best.
"I think it's very honest to say, 'Hey I've shot it, that's it, I'm not going to be any good any more'. It takes a brave man to do that."
Swann, England's most successful off-spinner with 255 Test wickets, has taken only seven in this winter's Ashes at a cost of 80 runs each.
Boycott added: "He knows he's not bowling well. The Australians have got him by the throat anyhow, they're whacking him around, he's not getting anybody out that matters. He knows all that.
"He's nothing to be ashamed about, he's nothing to be embarrassed about. He's been an excellent performer for England and I think he can hold his head up high."
Michael Vaughan, Boycott's fellow former Yorkshire batsman and his colleague on Five Live's commentary team, added: "There will be many cricket fans saying, 'Wait a minute, you signed up to play the whole of the Ashes tour yet you're doing one three games in'.
"But I think it's more the mind. I think the elbow problem (Swann has had three operations on his bowling elbow ) has just triggered the mind to suggest that enough's enough.
"I am surprised at the timing, I do think Swann had more cricket left in him, because I know what a wonderful bowler he is. I look to the next two years, England have got only 14 Test matches between now and the next Ashes series.
"There's a World Cup in 2015 which Swann would have been a part of so he is giving a lot away.
"I don't think he's been selfish, I think he's done it for his own mind, he thinks the team are better off without him."
Ex-England bowler Steve Harmison told Sky Sports 3: "He's going to be a miss because he's such a dangerous man for England when he's on song.
"I think he's going to be the last of his kind, he'll be the last one of the orthodox finger-spinners to make a real impact in world cricket."
Mick Newell, director of cricket at Swann's county Nottinghamshire, agreed England may struggle to fill the void but backed Swann's own tip to replace him - Durham's Scott Borthwick.
"For England, he leaves a massive gap because they haven't got that automatic replacement in that position," Newell told Sky Sports News.
"Borthwick's a good pick, if he gets a bit more bowling at Durham - he's tending to bat quite high up now and not bowl so much.
"Danny Briggs at Hampshire is an excellent young bowler who's had some international experience and I think (Simon) Kerrigan at Lancashire - I know he had a poor game at the Oval (in the final Test of the summer's Ashes) but I'm sure he's going to come back into the reckoning.
"They'll get a crack and Monty (Panesar) has two great opportunities at Melbourne and Sydney to secure a place."
As for Swann's future, Newell added: "I'd imagine that coaching would be far too mundane for him but he'll always be welcome at Trent Bridge.
"I expect that we'll see him launch a media career and I'm sure he'll be very successful."
Swann's opposite number in the Australia team, Nathan Lyon, paid tribute to his "unbelievable" fellow off-spinner.
"He's someone who I've looked up to a lot," Lyon told cricket.com.au. "His career stats stand for themselves, he's been an unbelievable spinner and someone who I watched pretty closely in my time.
"I'm sure he will be sorely missed in the England team but I wish him all the best in the future."
Australia paceman Ryan Harris added: "I don't know what to say, I thought he'd bowled okay in the series, just without luck I guess. I feel that we've played him very well too.
"Something's obviously not quite right with him, or he's fulfilled whatever he wanted to do, but to me that's a huge shock."