Janssen was selected to start for Spurs in their friendly match against Juventus earlier today.
However, the Dutch striker failed to get particularly involved in the match, which Tottenham lost 2-1.
Spurs were on the back foot for almost the entirety of the time when Janssen was on the pitch, and was not until the Dutchman was withdrawn that they started to show some attacking intent.
And Quinn said: “I felt sorry for Janssen, because he had departed by the time Spurs really got a stranglehold on the game. They were really bright, and they were moving goal-wards. The whole thing started to change.
“He was eager and desperate to make an impact at time when the rest of the players weren’t at the level they were after he came off.”
Janssen has built up a reputation as a predatory finisher, but he was given very little service by his Spurs teammates throughout the match.
One player who did impress slightly more in the contest was DeAndre Yedlin.
The American defender came on at half-time, and Quinn praised Yedlin’s display.
“He’ll want to impress after spending a year at Sunderland. He did a really good job out there today,” the Sunderland legend said.
Tottenham’s next friendly on their tour of Australia comes against Atletico Madrid on Friday morning.