But Walsh, rated Manly's best halves prospect in a generation, received Foran's tick of approval as the resurgent Sea Eagles continued to impress in the youngster's first start as an NRL player.
Jamal Fogarty's minor groin injury paved the way for Foran to hand a second NRL cap to 19-year-old Walsh after he made his debut from the bench late last year.
Against the runaway premiership favourites, Walsh never looked overawed despite months of speculation as to his possible role at the reconfiguring Manly this year.
After his side trailed 12-6 at halftime on Sunday night, Walsh threw one of the best no-look passes of the season to put in-form Haumole Olakau'atu into a hole.
Olakau'atu sprinted from the 40-metre line and found Ethan Bullemor, who equalised for the visitors.
Foran was equally impressed by Walsh's defensive efforts on his non-preferred right side.
"He was great. For a young guy to come into this sort of arena up against the team that's coming first, and he was pretty calm throughout the week," Foran said.
"He wasn't going to shirk it and he walked straight towards it tonight. I thought defensively he was outstanding.
"He came up with some really nice plays at certain times of the game and he'll only get better. He's a real future player for us."
With the Panthers up 18-16 in the final minute, Walsh had the ball in his hands outside the 40 metre line with a chance to send the game into extra time.
But his shot at a two-point field goal pulled up short, with Dylan Edwards marking the ball as the Panthers held on.
Ultimately, Manly were left to rue being unable to capitalise on 10 minutes with an extra man while Jack Cogger was sin-binned with 17 minutes to play.
His side up 18-16, Penrith's back-up hooker Cogger sat down in his 100th game for a high shot on Tolu Koula.
Manly had been excellent all night, overwhelming the usually clinical Panthers with their edge defence and overcoming the early loss of Kobe Hetherington (concussion).
But with Cogger off the field, Manly hurt themselves as Ben Trbojevic and Nathan Brown threw forward passes, and Lehi Hopoate spilled a ball into touch in his own red zone.
Manly remain in the top eight on a 4-1 start to life under Foran, and the coach lost none of his enthusiasm after the tight defeat.
"I learned that we've got a bloody good footy team here at the Manly Sea Eagles," Foran said.
"Yes, there's things that we can grow and we can get better at, but it makes me proud to know that they can go out there and go toe-to-toe with Penrith."
Manly had taken the lead earlier when Lehi Hopoate crossed on the left, with Penrith's Nathan Cleary incensed not to have been awarded a penalty for contact from Clayton Faulalo.
"I thought it was a pretty obvious obstruction," said coach Ivan Cleary.
The Panthers struck back when Edwards popped Izack Tago into a hole on the right side.
Tago started the season out of the team but has now scored two tries in two weeks as an impact back-rower starting from the bench, the most recent effort confirming victory.
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