Is Willi Castro a Better Defensive Option at Third Base Than Kyle Farmer?

When starting third baseman Royce Lewis injured his right quadriceps aggressively rounding second base (with hopes to score) on a double down the left-field line by star shortstop Carlos Correa, manager Rocco Baldelli's immediate response was to shift second baseman Kyle Farmer to third and insert left-handed hitter Edouard Julien into the game at second. Turning to Julien was antithetical to the platoon-happy lineup the Twins deployed against rising star left-handed starting pitcher Cole Ragans. That said, they had no other choice.

After Julien replaced Lewis in the third inning, the team's bench consisted of left-handed outfielder Matt Wallner, left-handed first baseman/designated hitter Alex Kirilloff, and right-handed backup catcher Christian Vázquez. Wallner, Kirilloff, and Vázquez all are basically unable to play third base, and the only other player on the field who could (Willi Castro) was stuck in left field with right-handed platoon mate Manuel Margot assigned to designated hitter duties. The Twins reacted to Lewis's injury as best they could, and although it ruined their initial plans for Ragans to face a near-exclusively right-handed lineup, their adjustments paid off, and the team concluded Opening Day with a 4-1 victory over Kansas City. 

Although the Twins handled Lewis's unexpected injury well at the moment, their course of action during his longish expected absence should deviate from what is currently perceived to be the plan. The Twins could hand Farmer the everyday job at third base until Lewis returns, and few would bat an eye. The former Cincinnati Reds starting shortstop is a steady veteran who can provide a meaningful sense of low-floor consistency (offensively and defensively) at the hot corner. This type of player possesses a lot of value, specifically this early in the season, but what if how Farmer is perceived doesn't match reality?

As noted earlier, Castro was relegated to left field on Opening Day, with Margot restricted to designated hitter and Wallner providing less value against left-handed pitchers. Leaving Castro in left field was the right decision, given the way the Twins lineup was constructed and the specific bench restrictions in place. Farmer deserves to receive some playing time at third base during Lewis's absence. However, Castro is the better option, and the Twins should hand him the bulk of the newfound opportunities. 

Last season, Castro played 219 innings at third base. During his time at the hot corner, the 26-year-old utility player had 52 attempts straight up, 14 toward the shortstop/third base hole, and 12 close to the line. Here is Castro's success rate compared to his estimated success rate in his attempts:

• Straight up: 81% success rate; 74% estimated success rate
• Toward the SS/3B hole: 64% success rate; 70% estimated success rate
• Close to the line: 67% success rate; 68% estimated success rate

Castro outperformed his estimated success rate straight up, performed below his estimated success rate toward the SS/3B hole, and nearly matched his estimated success rate close to the line. Showing exceptional range, Castro generated 3 Outs Above Average (OAA) at Baseball Savant, where 0 OAA is average. 

In 2023, Farmer played 276 1/3 innings at the hot corner, accounting for 57 2/3 more than Castro. The 33-year-old infielder had 33 attempts straight up, 30 close to the line, and 15 toward the shortstop/third base hole. So, despite playing nearly six-and-a-half more games at the position, Farmer received the same number of attempts at third base as Castro, with 78. Here is Farmer's success rate compared to his estimated success rate in his attempts:

• Straight up: 76% success rate; 74% estimated success rate
• Close to the line: 73% success rate; 74% estimated success rate
• Toward the SS/3B hole: 53% success rate; 66% estimated success rate

Farmer outperformed his expected success rate straight up, nearly matched his estimated success rate close to the line, and significantly underperformed his estimated success rate toward the shortstop/third base hole. Showing slightly below-average range, Farmer generated -2 OAA at Baseball Savant. Farmer performed well on balls hit to him and down the line, but struggled mightily on balls hit toward the 5.5 hole, performing 13 percentage points worse than expected. 

Farmer showed more of the same tendencies against the Royals on Thursday. After replacing Lewis at third base in the bottom of the third inning, Royals first baseman Vinnie Pasquantino chopped a weak two-out dribbler against starting pitcher Pablo López, toward Farmer at third. Farmer fielded the chopper and tossed it over to first baseman Carlos Santana to end the inning. Easy enough. Two innings later, Kansas City second baseman Adam Frazier chopped a similar ground ball toward Farmer, yet the result was less favorable for the utility infielder. Farmer bobbled the ball in his glove, allowing Frazier (who had a 31st-percentile sprint speed in 2023) to reach base safely on an infield single. 

Although Frazier's hit was inconsequential, these are the types of plays more skilled and agile third basemen with stronger arms (like Lewis and Castro) are more prone to making. Farmer immediately redeemed himself, fielding an almost two-hop groundball straight up from Royals designated hitter Nelson Velázquez and executing a flawless double play with second baseman Julien. Farmer isn't a bad defender, but his limited range and weaker arm make the non-routine plays at the hot corner more of a struggle. Castro would provide more defensive value at the position, having a stronger arm and more range. 

Do you agree that Willi Castro should be the primary third baseman in Lewis's absence? Join the discussion with a comment below.