Cardinals to call up prospect Jack Flaherty to start on Friday

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The Cardinals traded Mike Leake to the Mariners on Wednesday, which opened up a rotation spot. The club announced that prospect Jack Flaherty will be called up from Triple-A Memphis to start against the Giants on Friday in San Francisco. Friday, of course, is September 1, which is when rosters expand.

Flaherty, 21, was taken by the Cardinals in the first round (34th overall) of the 2014 draft. He’s the organization’s No. 3 prospect and No. 53 overall in baseball, according to MLB Pipeline. This season, between Memphis and Double-A Springfield, the right-hander posted an aggregate 2.18 ERA with a 147/35 K/BB ratio in 148 2/3 innings.