MLB: Spring Training-San Francisco Giants Workouts
Matt Kartozian / USA TODAY Sports

The San Francisco Giants are calling up one of the top pitching prospects in baseball. The Giants have summoned lefty Kyle Harrison to make his MLB debut Tuesday, the team announced. Tuesday will be the middle game of a three-game series with the Philadelphia Phillies at Citizens Bank Park.

Harrison, 22, missed about a month with a hamstring injury earlier this year and has struck out 13 in 9 1/3 innings spanning three Triple-A starts since returning. He threw 60 pitches in four innings last time out, so Harrison figures to be on a pitch limit Tuesday. For the season, the southpaw owns a 4.66 ERA with 105 strikeouts but also 48 walks in 65 2/3 Triple-A innings.

Our R.J. Anderson ranked Harrison the No. 25 prospect in baseball in June. Here's his write-up:

Back in the spring, we noted that Harrison needed to demonstrate he could consistently throw strikes (he'd walked 4.3 per nine innings for his career) and work deeper into starts (4.4 innings per appearance). Much to our chagrin, that hasn't happened. In his first 10 starts this season, Harrison instead walked nearly a batter per inning and averaged just three frames per attempt. His mechanics will likely prevent him from having even decent command as he has a lengthy arm swing that sees his elbow creep up to his shoulder line, elongating his operation and forcing his arm to play catch-up to his body at foot strike. Harrison has thrown significantly more strikes lately than he did in April, and it's at least possible that the new Double-A ball is to blame. The Giants have to hold out hope that he can locate his fastball-slider tandem just often enough to stick as a volatile starter.

For all intents and purposes, the Giants have two starting pitchers: Logan Webb and Alex Cobb. They have operated with a series of openers and bullpen games all season, with Anthony DeSclafani, Jake Junis, Ross Stripling, and Alex Wood providing bulk innings. DeSclafani (elbow) and Stripling (back) are on the injured list, however.

The Giants enter play Tuesday with a 65-60 record. They sit in the third wild-card spot, three games behind the Phillies.