The phrase "as he was progressing" is correct and usable in written English.
It can be used to describe someone's advancement or development in a particular context, often in a narrative or descriptive setting.
Example: "As he was progressing through the training program, he began to feel more confident in his abilities."
Alternatives: "as he advanced" or "as he moved forward".
Betances may be among the first of the injured Yankees to return this month, as Boone said he was progressing well after shoulder inflammation late in spring training.
I don't want to be [Jake's] coach, but I want to be alongside him as he's progressing as a player.
He's progressed as a young man and young leader.
"When you think about how he's 23 years old and how he's progressed as a pitcher, how he's taken his great gift and put in the work to refine it, that says a lot about him," Colletti said.
The president would still retain unlimited waivers to stave off the escalating pressure as long as he could verify that talks are progressing.
He had been progressing as a playmaker or an all-around midfielder but this was, as everyone soon discovered, his destiny.
Andersen, for all his folk roots and naivety, always saw himself in the European vanguard, and was as enthusiastic about technical experimentation in the arts as he was about technological progress in society.
It seems like you guys are getting tougher as you're progressing as a band.
New films such as "Spot" are progressing us forward.
One can either interpret this sentence as "He has progressed a lot, but he is still a person of the second rank (as he was before)" or "He has progressed a lot, but he is still a person of the second rank (if he were given an evaluation)".
He was stern at times, witty at others, always in command, his mood swinging from anger over Iraq's treatment of POWs to impatience with one journalist's rambling"Is that a statement or a question?" he snapped--to self-assurance that the war is progressing as he planned.
