The first-year closer struck out Toronto's Brett Lawrie looking at a 79-mph hook in Wednesday's 3-2 win, then followed by getting Colby Rasmus swinging at the same pitch before procuring his 26th save.
After a recent rough patch with his command, Wilhelmsen said his confidence in the curve has returned.
"I've been struggling with that curveball as of late," he said. "But I said something the other day about how I just need to keep throwing it out there and keep throwing it until [the struggles were] gone. So that's what I did."
Wilhelmsen had back-to-back one-run saves in the first two games of the Blue Jays series, giving him 19 saves in 20 opportunities since the All-Star break, the most in the AL in that span.
"He did a nice job working through a couple tough days," said manager Eric Wedge. "That's the true test of a closer. We've seen him steadily work his way back and he's been real good the last three outings or so. He seems much more relaxed, the ball is coming out of his hand the way you like to see it, he's confident in all his pitches. Those aren't easy save opportunities we're seeing him get and he's doing a great job for us."
As for the curveball? The same unpredictability it brings to opposing hitters makes Wedge uncomfortable at times, as well, but he's learning the benefit of that pitch in tough situations.
"It's huge for him," Wedge said. "The confidence he has in it is just as important. Sometimes it makes me a little nervous, but he's comfortable throwing it at any point, as he's proven time and time again. The confidence he has in that pitch is tremendous. And now he mixes in the changeup to left-handers, and that's been a good pitch for him, as well."
For Wilhelmsen, it's all pretty simple.
"I'm hitting the strike zone," he said. "That's all I can ask for right now."