Three starters who could replace Jack Flaherty

St. Louis Cardinals starting pitcher Jack Flaherty went down last week with a strain in his right shoulder. This is the second time this season that Flaherty’s right shoulder has sent him to the injured list, with this injury carrying no timetable for a return. As a result, the Cardinals are going to have to look into options to fill his spot in the rotation, potentially for the rest of the year. Down below we are going to look at an internal and a couple of external options that the Cardinals can replace him with.

Matthew Liberatore

Liberatore presents the most likely replacement for Flaherty seeing as he is an inhouse option. If St. Louis does not want to sacrifice prospect or financial capital, Liberatore is their guy. As highlighted in one of my recent articles, his first four starts with the big-league club were rough from both the eye test and when evaluating the analytics. Despite this though, the Cardinals view Liberatore as a big piece of their future and giving him an extended run at the big-league level will be a great way of determining whether or not they have something in the southpaw.

Luis Castillo

Castillo would not only be a replacement for Flaherty this year, but he would also be Adam Wainwright’s replacement for next season, which gives the club added incentive to bring in the Red. His xBA, wOBA, xSLG percentage and xERA are all in the 60th or better percentile, including his xERA, which sits at 3.43. Something that has to be factored into Castillo’s numbers being the worst they have been in recent years was the rust he showed at the beginning of the season as he returned from a shoulder injury. In his first three starts back he allowed eight runs, four walks, and 14 hits to go along with 12 strikeouts over 15 ⅔ innings. Although, in his last eight starts, he has only given up 14 earned runs on 37 hits, with a 54:18 strikeout-to-walk ratio over 48 ⅓ innings. Ideally the walk total would be a bit lower; however, historically, he has always been a pitcher that has sat around a nine percent walk rate.

There are two things that stand in the way of Castillo becoming a Cardinal. The first being the price; Castillo is going to be one of the most sought-after arms on the market this summer and could spark a true bidding war that the Cards simply might not want to get involved in. The second thing being the fact he plays for the Reds, who might not want to send him to a division rival where he would almost certainly pitch in the next two postseasons whilst they sit at the bottom of the division.

Kohl Stewart

Stewart, the former fourth overall pick in the 2013 MLB draft, represents a zero-risk signing for the Cardinals. Stewart has three seasons under his belt with largely below average numbers. His best xERA, which was a 4.54, came all the way back in 2018. His career average exit velocity against is 89.9 MPH, and his career strikeout rate is 13.6 percent. Despite those numbers I do think there might be some magic left to uncover in Stewart’s game. Stewart’s slider spin rate from last season would be tied for 99th out of 345 pitchers to throw at least 250 pitches this season. Following the same criteria as his slider, his curveball would be tied for 75th out of 282 pitchers. Both pitches have below average vertical movement but above average horizontal movement.

Obviously, for a starter, having a slider and curve is not enough to get through a lineup twice. However, if Stewart was to throw both pitches at a far higher rate than 8 and 3.1 percent, respectively, they could make his cutter and sinker more effective, as they would be playing off of them. Additionally, completely scraping his four seamer and changeup — two pitches that rank well below average in multiple metrics — would make his overall arsenal stronger. A plus-curve and slider, paired with an average sinker and cutter, is something that can trouble hitters for four to five innings.