The SF Giants made a surprise move by promoting Jonah Cox to the major league roster. In a corresponding roster move, Ryan Borucki was designated for assignment, thereby ending an experiment that never should have taken place.
This sounds harsh, and it has more to do with the front office's decision to sign him in the first place than Borucki himself. He joined the Giants late in the spring after he had been told by the Chicago White Sox that he would not make the team.
Admittedly, the Giants were entering the season with some level of uncertainty with the left side of the bullpen. Matt Gage was healthy and put together a good spring, but Erik Miller missed the first half of camp and Sam Hentges was not ready until the middle of May.
The Giants had other options. Joey Lucchesi rejoined the club late in the spring on a minor league deal. He was released shortly after the Borucki signing. Carson Whisenhunt and Juan Sánchez were lower on the depth chart for left-handed pitchers, and the Giants wanted the former to get stretched out as a starter. This is to say that they had options.
SF Giants misread Borucki's skill set as one that could fit in modern baseball
Fortunately, Miller was ready to go, and the Giants expected him to fill a leverage spot in the bullpen. Gage was penciled in as more of a situational lefty, along with Borucki. It is fair to say that Gage and Borucki filled somewhat redundant roles in the bullpen.
The big difference is how they performed against right-handed hitters. Gage and Borucki both had strong splits against left-handed hitters. That said, in the few spots that they used Borucki, he rarely came through.
Overall, the left-handed reliever did well in those matchups. Left-handed hitters posted a .550 OPS against him, but he was unplayable against right-handed hitters. In 55 plate appearances, opposing hitters had a 1.085 OPS in those matchups.
On more than one occasion, Tony Vitello picked a good spot to use Borucki with a left-handed hitter coming up. However, he was unable to get the job done, leading to a suboptimal matchup against a right-handed hitter. In hindsight, those moves would look questionable, but that has more to do with the reliever not getting the job done.
That was the problem with having him on the roster in the first place. He was unplayable in a specific matchup in an era where relievers typically have to pitch to a minimum of three batters. At the very least, one of those batters is going to hit from the right side.
There was a time when Borucki's skill set could work in baseball, but that time has passed. When Sam Hentges returned from the injured list, Borucki remained on the roster, even while carrying three other left-handed relievers on the roster. It was an oblong fit. The Giants have now moved in a different direction, but that experiment probably did not need to take place.
