"I think this is just a huge accomplishment for me," Weaver said. "Obviously, this is what we dream for as a kid, and it coming true is just crazy. I'm trying to wrap my head around it and stay even-keeled and trying to go with the flow."
Weaver earned the opportunity to replace Wacha because of what he did at Double-A Springfield this season. Ranked as the organization's No. 2 prospect by MLB Pipeline, Weaver posted a 1.40 ERA and a 0.95 WHIP in 12 Double-A starts. That earned him a promotion to Triple-A Memphis earlier this week, where he threw six scoreless innings in a start on Monday.
Weaver learned that he would be promoted again one day later.
"He made a really positive impression in [Spring Training]," manager Mike Matheny said. "I like what I see, and obviously the numbers this season have supported that this kid goes out and makes good pitches. Every time you bring a kid in and give him a start right out of the box, it's a tall order. But there are some guys who thrive with that opportunity."
Weaver arrives with a different repertoire than what Matheny saw in Spring Training. After toying around with a cutter in camp, Weaver continued to throw it while waiting for his fractured left wrist to heal in April and May. By the time he was cleared to join Springfield in early June, he was ready to feature the fourth pitch.
It has since become a reliable weapon.
"My first outing, I just started throwing it like I had had it for 10 years," Weaver said. "I felt comfortable with it. After that start, I was like, 'This pitch is capable of doing something good for me.' I kept throwing it, and it's just been huge. [It] has really helped me get some strikeouts and get deeper in the game."
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Read her blog, follow her on Twitter, like her Facebook page and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.