"This Munster team that is starting to develop is one that knows it has the reserves to call upon when we need to be able to dig deep. There is no doubt that this could be an important factor heading into the latter part of this month," said Penney.
"We're going to have to really dig deep. The outcome against Leinster wasn't what we wanted but we certainly couldn't be too critical of the performance."
Munster lead 16-12 but despite out-scoring their opponents two tries-to-one, through Felix Jones and Ian Keatley, Amlin Challenge Cup semi-finalists Leinster rallied to win 22-16 at Thomond Park.
"It was a Leinster-Munster fixture. We came off a massive emotional high over the last ten days, building into the Harlequins game and then a six-day turnaround for the lads to get back on the horse and perform," added Penney..
"I couldn't have been prouder. Yes, we could go back and pick out some errors and some little turning point moments but the attitude was there, the commitment to the jersey and the province was there. It was just a tight game in which we didn't take some opportunities, they took theirs and that's the difference. The game could have gone either way.
"What disappointed me most was that the boys weren't rewarded for their efforts, to be able to put in a performance like that and get no reward for it is the most disappointing thing."
Munster were also relieved to hear the news there will be no citing complaint against lock Paul O'Connell following his clash with Leinster wing Dave Kearney in the second half.