The 21-year-old prop, who joined the club this summer under their Player Development Foundation scheme made his debut in the weekend win over Ospreys.
"He had a nasty injury early on and he came back and we weren't happy with his fitness and form," Paver said.
"He went to Redruth and I had a few doubts, we had a frank conversation and he's taken the bull by the horns."
The former Launceston player spent the 2014-15 season with Plymouth Albion in the Championship, but did not start a league game during the Devon club's relegation season.
But Paver says Chapman's performance in the British and Irish Cup win on Saturday has raised some eyebrows at the Mennaye.
"I left him out there for 80 minutes, started him at loose-head, pushed him to tight-head, not many can do that but he can do that, and he put his hand up and he's really impressed me," he added.
"The guys will give him a big slap on the back because he's valued within our squad and he's got an opportunity next week to back it up and that will be great for this young man.
"The Championship is not an easy place to play your rugby and the British and Irish Cup is a good place to start from. If he can impress next week who knows."

Samuel Tweed, 74, from Mark Street in Newtownards, County Down, had also admitted possession of a haul of guns along with 2,500 rounds of ammunition.
He escaped from custody at Belfast Magistrates' Court in May 1974 when he was facing firearms charges.
He had been arrested in connection with the discovery of a weapons cache in the city the previous month.
The haul included 10 revolvers, nine pistols, a sawn-off shotgun and assorted ammunition.
Tweed was 32 when he escaped after a group of men entered the courtroom and claimed there was a bomb in the building.
He remained undetected until his arrest in 2012.
First Minister Peter Robinson was one of a number of DUP politicians who wrote letters urging the judge not to jail Mr Tweed.
The court also heard that the great-grandfather had led a law-abiding life since his escape and was suffering from bad health.
The judge told the court that although Tweed was a younger man when the offences were committed, that did not diminish their seriousness.
"I am satisfied that you have lived a lawful and law-abiding life over the last 40 years," he added.
"However, that does not mean that the offences are any less serious; far from it.''
Cornish Pirates coach Alan Paver says he has been impressed with Luke Chapman's commitment after injury.
[NEXT_CONCEPT]
A pensioner who escaped from a court more than 40 years ago has been jailed for two and a half years.