Wilshere this week controversially withdrew from Pearce's squad for next month's European Under 21 Championships after becoming convinced he was risking injury by extending what has already been a 53-game season.
Thanks, but no thanks: Wilshere has turned down the chance to represent England this summer
It represented a dramatic U-turn from the Gunners midfielder, who had repeatedly declared his intention to play at the finals in Denmark.
It was also a major blow and an embarrassment for Pearce, who had been adamant when naming Wilshere in his 40-man provisional squad earlier this month that the 19-year-old would travel.
Wilshere changed his mind after being shown statistics by Arsenal's medical department which indicated he was becoming fatigued.
But Pearce said: 'I would say that every player at this stage of the season would be reasonably tired.
Breakthrough year: The Arsenal midfielder has played over 50 games for the Gunners this season
'I'm talking about Spanish internationals, who we have to face, Czech internationals, who we have to face.
'Across the board at the end of a long season, players are more susceptible maybe to injury.
One eye on the future: Wilshere is keen to give his body a rest
'One thing's for sure - Arsenal have not left him out of the side in the last six weeks of the season, even though the stats have said he's in red zone.'
Pearce otherwise refused to be drawn into a club-versus-country row, rejecting the suggestion Wilshere had been frightened into pulling out by his club.
'I think Jack's got his own mind,' said the former England left-back, who also insisted he had not been angered or hurt by the teenager's U-turn.
Pearce delayed naming his 23-man squad until after Sunday's final round of Barclays Premier League games, which saw Arsenal finish fourth, forcing them to play a qualifying round to get into the Champions League group stage.
He played down the impact the Gunners' earlier start to next season might have had on Wilshere's decision.
'Arsene didn't want him to go full stop,' he said, also insisting it would not upset him to see Wilshere play a full part in his club's summer tour of Asia.
'What he does with Arsenal next season is irrelevant to me.'
Andy Carroll was the other big-name absentee when Pearce announced his final 23 on Monday. The Liverpool striker was ruled out through injury but there have been question marks over his commitment to Under-21 football.
Pearce was reluctant to speak at length on Carroll, saying only: 'I've not got a problem with any of the players with the Under-21s.'
Pearce suffered another blow today when another player with senior experience, Micah Richards, withdrew from the squad due to a hamstring problem. Manchester City right-back Richards reportedly had been earmarked as captain.
Pearce said: 'We felt it was too much of a risk to wheel him out, with the possibility of it breaking down again. 'It wouldn't be fair on another player that would be fully fit.'
He added: 'He's a big member of the Under-21 party. 'He played in the final, obviously, two years ago. He'll be a big miss for us.
'For me, at this stage, it's all about the 23 that are fit, available and ready to come and contribute.'
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