With Hunter Stratton injured, the Pirates need to make this waiver claim

The Pirates just lost a solid reliever in Hunter Stratton. To replace him, the Pirates should look to claim Diego Castillo, a veteran reliever who was recently designated for assignment.
Minnesota Twins v New York Yankees
Minnesota Twins v New York Yankees / Luke Hales/GettyImages

In the final game against the Cardinals, the Pirates lost a solid right-hander in the bullpen to an injury. After throwing his seventh pitch, Hunter Stratton immediately signaled to the dugout that he was injured. It turned out to be something with his throwing shoulder, which may result in time on the injured list.

Losing Stratton is significant as he has been one of the Pirates' go-to relievers in certain situations. On the season, Stratton has a 2-1 record with a 4.26 ERA and 1.11 WHIP in 31.2 innings pitched with 30 strikeouts. Opponents had a batting average of .242 against him.

He actually has gotten very unlucky this season. His expected ERA is at 2.68, which is significantly lower than his actual. His expected opponents batting average is also at .216, and his chase rate is at 34%. These statcast metrics show that Stratton is much better than his stats indicate.

How should the Pirates replace Hunter Stratton in the bullpen?

The Pirates bullpen depth has already been tested this season after losing Dauri Moreta and Ryan Borucki to injuries. Recently, the Pirates added Dennis Santana and Justin Bruihl to the major league bullpen, along with multiple moves to the minor league pitching staff.

Now that the Pirates are down another arm, they need to figure out how they will replace him. There are not many options in Triple-A, which leaves the Pirates with no choice but to look externally. The Minnesota Twins recently designated Diego Castillo for assignment, who is a veteran right-hander that Ben Cherington should be trying very hard to acquire.

Castillo has been in the league for seven seasons and has always been among the top relievers. Despite being solid for multiple seasons, he has recently battled various injuries that has prevented him from pitching consistently. Since the start of 2023, Castillo has only thrown 15.2 innings in the major leagues. He has battled through three separate shoulder injuries, which dropped his fastball velocity to a career low in 2023 to around 94.7 MPH.

But now it has risen back up over 95 MPH in his short stint in the major leagues. Along with the shoulder issues, came control issues. In 2018-2022, Castillo had very good control, with a walk percentage of 8.9%. Although this has recently increased in the last two seasons to 19.7%, it is not going to remain a consistent problem. His walk percentage in Triple-A this season was 8.9%, the same as how it was when he dominated with the Rays and Mariners.

So far in 2024, Castillo has a 2.50 ERA, 2.97 FIP and 1.05 WHIP with 22 strikeouts in 18 innings pitched at Triple-A. Opponents are batting just .194 against him. These numbers are convincing, but with the Twins it was different. Although his ERA in MLB was good at 2.57, he also added a 5.29 FIP and a 1.71 WHIP.

Now that Diego Castillo is healthy, the Pirates should do their best to get him. Although he has struggled in recent major league stints, he is still a solid arm that the Pirates should not let go unclaimed.