The Saints clinched a semi-final place with a 36-20 win over Widnes, and will now face Leeds for a place in the final.
“Swifty is probably the only person I know who can get stretchered off one week and then score a full length try the week after!” Walmsley said.
“Fair play to him, it was a cracking try. He’s turning into a great little player.”
As for the draw against Leeds, Walmsley is taking it in his stride, with all games bound to be tough once a team reaches the semi-finals.
“We’re happy to be in the hat,” he said.
“But maybe not too happy with the performance. Once you’re in the hat anything can happen.
“You’ve got to meet the best teams at some point in the Cup, if you want to go and win it.
“So whether we’d got tgen in the semis or they’d made the final by another route, we’d have probably had to play them at some point.
“We don’t mind the tough games.”