Pennock included the experienced quartet of Alex Bruce, Yannick Sagbo, Liam Rosenior and Eldin Jakupovic in Monday's Under-21 Premier League Cup defeat at Middlesbrough.
Despite the 1-0 loss at the Riverside, the fringe stars, including Bruce on his return from a troublesome hamstring injury, gained priceless game-time ahead of a testing Christmas period in the top flight.
With Harry Maguire also gaining his first full outing in over a month, Pennock says manager Steve Bruce will be boosted by a cumulative 450-minute display from the five stars.
"The gaffer (Bruce) needs players who are match-fit to go into his team whenever they are required," Pennock told the Mail.
"Alex is one of a number of them. It was great to see Alex back on the field after his injury.
"Yannick's been out on loan and hasn't had a lot of game-time. He needed to play and the roles in this side were the same.
"Harry needs games as well. He's picked up a little knock but we're hoping it's not too serious.
"With Eldin he's always keen to play when he can. Our youngsters can look at those players and see what they do day in, day out and speak in the dressing room, as well as listen to the words they say."
The test of Manchester United this weekend may come just too soon for defender Bruce, 30, despite coming through the clash at the Riverside unscathed.
But one player who backed up just 24 hours after a bruising cameo against Spurs was Liam Rosenior.
Following a 25-minute spell in the 2-1 defeat to Mauricio Pochettino's men, Pennock was delighted to see Rosenior's attitude spread amongst his academy squad in a committed showing on Teesside.
"It's all down to Liam's dedication and professionalism and that's what gets you a long career," Pennock added, lauding the work ethic of the 30-year-old after his involvement with the academy side in 2014.
"You have to be dedicated to your career and it is a massive one. You have to take full responsibility to make the most of it.
"It's important these senior lads do come in and be professional with us.
"They always are and that's a real credit to them, and long may it continue for us."
