ST. LOUIS -- Arguably the most dominant pitcher in the organization's Minor League system this year, Luke Weaver joined the Cardinals on Monday for his first callup of the season. The club optioned Mike Mayers to create roster room for its third-ranked prospect.
Though Weaver made eight starts for the Cardinals last season, he is earmarked for a bullpen role now. Manager Mike Matheny emphasized that Weaver will not be held back as a long reliever, but will instead be considered a relief option for any situation. The Cardinals wasted no time getting Weaver involved, either, as he came in behind Adam Wainwright on Monday. Weaver allowed two hits in a scoreless inning in the Cardinals' 14-6 win over the Marlins.
He stranded two runners after getting slugger Giancarlo Stanton to line out to center on a 2-0 changeup. 

"We don't want to take him out of the Triple-A rotation to have him just sit down there and be an emergency backup guy," Matheny said. "I plan on pitching him and throwing him into situations where we feel he'll help us out."
Weaver has performed well in Memphis this year, going 7-1 with a 1.93 ERA in 11 starts. He's walked 13, struck out 60 and allowed three home runs in 56 innings. Most recently, Weaver posted a 1.59 ERA in four June starts.

"[I've been] just waiting for the opportunity to come and just being patient and trying to do my part down there and just to improve and fine-tune my skills," Weaver said. "When [I'm] called upon [I'll] try to do some successful stuff here."
Though he's been deserving of a promotion for some time, Weaver was passed over previously because of both injury and bad luck. Twice, Weaver was sidelined with back stiffness. Other times, he wasn't fresh when the Cardinals needed an arm.
Weaver made his Major League debut last August and finished 1-4 with a 5.70 ERA and 1.596 WHIP. He opened his big league career by allowing three or fewer runs in each of his first six starts, but was pulled from the rotation after two abbreviated mid-September performances.
Weaver has since said that one of his downfalls as a rookie was giving Major League hitters too much credit. The Cardinals have challenged him to pitch more aggressively this time around.
"It's just part of the progression of a young player and a young pitcher," Matheny said. "Trust your stuff; [his] stuff is good. Jump in there and attack the strike zone and trust your defense. His stuff should play here as well as anywhere else."
The Cardinals made this move on Monday because Mayers, who threw three innings in relief on Sunday, was not going to be available to pitch for at least two days. Mayers had made two appearances since his June 25 callup, as the Cardinals were saving him for long-relief opportunities.
They won't do the same with Weaver, and, Matheny said, they don't plan to slide Tyler Lyons back into that role either. John Brebbia and Matt Bowman are two relievers Matheny mentioned when naming other alternatives should the Cards need someone to cover multiple innings.