The Bombers had three players on the bench when the siren rang after Paddy Ryder (knee), Dustin Fletcher (hamstring) and Courtenay Dempsey (hamstring) all picked up injuries throughout the match.
There were also plenty of Bombers playing sore, with Jobe Watson, Brent Stanton and Andrew Lovett all spending long periods on the bench.
Knights said his side's "resilience" and ability to withstand St Kilda's fourth-quarter charge was the most pleasing part of the win.
"We always knew St Kilda were going to come, and we were out on our feet with 10 minutes to go," he said after the thrilling win.
"Thankfully, we were able to hang on.
"When Brent Prismall wrapped that ball around the post, my heart was beating a few notches up from what it normally does.
"It was a great win for the club, and I said to the guys (that) the 22 players that represented our club today did us proud. We came with a plan to win, and we had a belief that if we did everything right we could win.
"The players followed through on the plan."
Knights admitted he thought the game was lost when Saints captain Nick Riewoldt lined up after the siren with the chance to steal the win.
"It is difficult because it was a 45-degree angle, 45m out, so it's a 50-50 shot. It's a tough shot," he said.
"I was watching him kick them in the warm up, and he was kicking them pretty well.
"I thought he'd strike it, but it was a tough shot and thankfully he missed it."
Knight said his endeavour to teach his young players to "believe they can win and to take the game on" was starting to pay dividends.
"Sometimes it hasn't worked for us, and we've really been smashed in games," he said.
"They always had a belief and a spirit they could win, so we thought we could do well here today as long as we supported each other and we used the ball well.
"Being three goals down early, it would have been quite easy for the guys to go back into their shells but thankfully they didn't and they kept fighting, got us back on even terms, and we went on from there."
He added he was more focused on ensuring his young side's state of mind remained sound next week.
"The big challenge now is for this group to understand they've got to present the same attitude and mentality to every side like we played against St Kilda today," he said.
"We haven't been able to establish that this season thus far.
"We're still battling with our maturity and our inconsistency, but we've showed during the year we can match it with the better sides. We've been hurt by sides that have been beneath us on the ladder.
"We really have to present with a strong attitude next week and the week after."
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