Amir's career was significantly hindered after being banned for five
years between 2010 and 2015 for his involvement in a spot-fixing
scandal, in which he and fellow fast bowler Mohammad Asif were bribed to
deliberately bowl no-balls in a Test against England in 2010.
During that time, Amir did not keep himself in shape, something which
Arthur believes has attributed to him retiring from red-ball cricket at 27.
Since returning in 2015, Amir has had to manage a heavy
workload, especially in recent times in the England and South Africa
series, which has taken a toll on his body.
"He (Amir) had five years out of the game. In those five years, he
didn't do anything. His body was not up to the rigours of day in, day
out Test cricket," Arthur told ESPNCricinfo.
"We pushed him as much as we could during the England and South
Africa series, because he is such a good bowler whom we wanted during
those tours. We've tried everything we possibly could with Amir.
"He could have managed those five years better. He'd be the first one
to acknowledge that. But I understand where he was in his whole life,
so it was a tough period for him. I understand all that," Arthur said.
Having made his Pakistan Test debut at 17, Amir took 51 wickets
in 14 Tests at an average of 29.09 before the ban and upon his return
claimed 68 wickets in 22 Tests at an average of 31.51.
Arthur believes that if it were not for that ban, Amir would have
been one of the most successful fast bowlers in Pakistan cricketing
"The Amir hype all those years ago was justified because he is a quality bowler," he said.
"When the ball swings there's not much better but he's not the
bowler now that he was in 2009 and 2010. He was different, his body was
"But had he not had those five years out of the game, I think he would be
up there with the very best Pakistan have ever had," he said.
The South African admitted that the left-arm fast bowler had been mulling over the decision for over a year.
"It was on the cards for a long while. Amir had been speaking to me
about it with me for some time now. His Test career was taking a strain
on his body," Arthur said.
"It's not about management here. It's about his desire to play Test
cricket and the effects it has on his body. reluctantly I accepted his
decision because that's what he wanted to do and that's what he thought
was best for himself."