Saunders, in what was his first game in charge, handed the 19-year-old his first senior start for Wanderers in Friday night's 1-1 draw against Blackburn at Molineux, and Cassidy put in a solid shift as he completed 79 minutes before being replaced by Sylvan Ebanks-Blake.
"I thought Jake was magnificent, Jake and Kevin Doyle caused all sorts of problems," Saunders said.
"People might say he wasn't that good but, in my eyes, what I asked him to do he did - his effort, determination, on the move, challenging players.
"He's playing against two Premier League centre-backs, that's the biggest game he's played in and I thought he was brilliant. And he was unlucky, the 'keeper has made a brilliant save from his volley."
The teenager is back with Wolves having banged in 11 goals in 28 starts during a loan spell with League One side Tranmere over the first half of the season.
Saunders has made his desire known to strengthen Wolves' attacking options but he remains a big admirer of Cassidy's ability.
And former Liverpool and Aston Villa striker Saunders, who is fourth on Wales' list of all-time scorers with 22 goals from 75 games, has been taking part in finishing practice with the Wales Under-21 international at the club's Compton training ground to help hone his skills.
Saunders added: "We've got 40 players and there were only three strikers available - Kevin, Sylvan and Jake. We're a bit unbalanced as a squad, it's obvious. And Sylvan was feeling his hamstring a little bit so I didn't want him to be out for three or four weeks by trying to get through that game.
"I've watched Jake, he's fit, he's been scoring goals for Tranmere and I've been finishing with him (in training) for three days and he's got real hammer feet when he strikes the ball. He can score from anywhere."